kinyuusita yousi wo sumaho de totte, saki ni sousinsite okimasita.

A natural breakdown is:

• 記入した用紙を = the form/paper that I filled out
• スマホで撮って、 = took a picture of it with my smartphone, and...
• 先に送信しておきました。 = sent it ahead of time / sent it in advance

So the sentence is basically:

• [I] took a photo of the filled-out form with my phone and sent it in advance.

Japanese often leaves out the subject when it is obvious from context, so I is not stated explicitly.

Because in Japanese, a clause can directly modify a noun, and it comes before the noun.

So:

• 記入した用紙 = the form that was filled in / the filled-out form

Here, 記入した literally means filled in or entered/wrote on, and it modifies 用紙.

This is very different from English word order. English says:

• the form I filled out

Japanese says:

• I filled out form → 記入した用紙

This is a very common Japanese pattern:

• 買った本 = the book I bought
• 昨日見た映画 = the movie I saw yesterday
• 日本で撮った写真 = the photo I took in Japan

In noun-modifying clauses like this, the tense shows the relationship to the noun.

• 記入した用紙 = the form that has been filled out
• not just any blank form, but specifically the one after the filling-in is already done

So the past form does not necessarily mean the whole sentence is talking about a distant past event. It means:

• the act of filling out happened before the form is being referred to as a filled-out form

If you said something like 記入する用紙, that would sound like:

• the form that will be filled out
• or the form to fill out

So 記入した is the right form for a form that has already been completed.

Here 撮って is the て-form of 撮る.

With cameras and phones, 撮る means:

• to take a photo
• to film / record

So スマホで撮って means:

• take a picture with a smartphone
• more naturally in English here: take a photo of it with my phone

The object of 撮る is omitted, but it is understood to be the form:

• 記入した用紙をスマホで撮って = take a picture of the filled-out form with a smartphone

Japanese often omits things that are clear from context.

Because で marks the means/tool/method used to do something.

So:

• スマホで撮る = take it using a smartphone
• ペンで書く = write with a pen
• 箸で食べる = eat with chopsticks
• メールで送る = send by email

Here, スマホで means with a smartphone or using a smartphone.

It can be omitted because it is understood.

Japanese often allows this kind of shortening:

• 写真を撮る = to take a photo
• but in context, just 撮る can already imply take a photo of it

So:

• 用紙をスマホで撮って is understood as
• take a photo of the form with a smartphone

This is very natural in everyday Japanese, especially when the thing being photographed is already obvious.

The て-form connects actions.

Here:

• 撮って、送信しておきました = took a photo and sent it in advance

So the flow is:

1. filled out the form
2. took a photo of it
3. sent it ahead of time

The て-form often works like:

• and
• then
• after doing that

It does not always show strict chronological order in every sentence, but here it clearly does.

先に means something like:

• first
• beforehand
• ahead of time
• in advance

In this sentence, it gives the nuance that the sender did the sending before some later step.

So 先に送信しておきました suggests:

• I sent it ahead of time
• I went ahead and sent it first
• I sent it in advance, before the next step

It often implies there is some later expected action, such as:

• submitting the physical paper later
• waiting for confirmation later
• doing this now so things go more smoothly

This is a very important grammar pattern.

• 〜ておく means do something in advance or do something and leave it done for later convenience/preparation
• 〜ておきました is the past polite form

So:

• 送信しました = I sent it
• 送信しておきました = I sent it in advance / I went ahead and sent it

The nuance is not just that the action happened. It suggests:

• it was done as preparation
• it was done before it became necessary
• it was done to be ready for what comes next

That nuance is one of the most important parts of this sentence.

They are similar, but not identical, and using both is very natural.

• 先に focuses on before something else / earlier
• 〜ておく focuses on doing something in preparation

So together they reinforce the meaning:

• 先に送信しておきました = I went ahead and sent it in advance

You can think of it as combining:

• timing: earlier than the next step
• purpose: for convenience/preparation

Using both makes the speaker’s intention especially clear.

送信する means:

• to transmit
• to send electronically

So it is commonly used for things like:

• emails
• messages
• files
• online forms
• digital images

Since the sentence is about taking a photo with a smartphone, 送信しておきました sounds very natural because it suggests sending the image digitally.

By contrast:

• 送る is more general: send
• 送信する is specifically more like send/transmit electronically

So 送信 matches the smartphone/photo context well.

The object is omitted, but it is understood from context.

Most likely, what was sent is:

• the photo of the filled-out form or possibly
• the filled-out form image/data

Japanese often omits objects when they are obvious. So even though the sentence does not explicitly say:

• 写真を送信しておきました that is probably what is meant.

No. The particles make the roles clear.

• 記入した用紙を = the thing being acted on
• スマホで = the tool used
• 撮って = take a photo

So the meaning is:

• I photographed the filled-out form using my smartphone

The を marks the main thing involved as the object, and で marks the instrument/tool.

By itself, 送信 strongly suggests something electronic was sent, not the physical paper.

Because the sentence says:

• fill out the form
• photograph it with a smartphone
• send it

the most natural interpretation is:

• the photo/image of the form was sent

If someone physically mailed the paper, Japanese would normally use a different expression, such as:

• 郵送しました = mailed it
• 提出しました = submitted it

So here, the digital-photo interpretation is the natural one.

Because Japanese often omits the subject when it is already clear.

In this sentence, the default understanding is:

• I filled it out
• I took the photo
• I sent it

Adding 私が would usually only be necessary if:

• you want emphasis
• there is contrast
• the subject is unclear

So the omission is normal and natural.

It is polite, but fairly everyday in style.

Politeness comes from:

• おきました rather than plain おいた
• 送信しておきました rather than plain 送信しておいた

At the same time, words like:

• スマホ = casual shortening of smartphone

make it feel conversational rather than stiffly formal.

So overall it sounds like:

• normal polite spoken or written Japanese

If you wanted a more formal word than スマホ, you might use:

• スマートフォン or depending on context even
• 携帯電話 / 携帯

But スマホ is extremely common.

Yes. 先に is flexible.

Depending on context, it can mean:

• first
• before that
• ahead of time
• earlier

In this sentence, it most naturally means:

• ahead of time / beforehand

But the exact nuance comes from context. For example, it could imply:

• I sent it first, and then I’ll do the rest later
• Before bringing the actual form, I already sent the image

So 先に is not just a dictionary word-to-word in advance; it often points to the order of actions in a practical sense.

The difference is mainly nuance.

• 送信しました = I sent it.

  • simple statement of fact

• 送信しておきました = I sent it ahead of time / I went ahead and sent it.

  • suggests preparation
  • implies this was done intentionally before it was needed
  • can sound slightly considerate or efficient

So if someone is reporting that they already handled something proactively, 〜ておきました is a very natural choice.