حتما قبل از رفتن به من پیام بده تا منتظر تو باشم.

حتما means definitely, for sure, or be sure to.

In this sentence, it adds emphasis to the request: حتما ... پیام بده = Be sure to message me / Definitely message me.

You may also see it written as حتماً. Both spellings are common.

After قبل از (before), Persian very often uses an infinitive/verbal noun rather than a fully conjugated verb.

So:

• قبل از رفتن = before going / before leaving

This is a very common structure in Persian:

• قبل از خوابیدن = before sleeping
• بعد از رسیدن = after arriving

A more explicit alternative would be:

• قبل از این‌که بروی / بری = before you go
• قبل از رفتنت = before your leaving / before you leave

So قبل از رفتن is normal and natural.

It can mean either, depending on context.

The basic meaning of رفتن is to go, but in many situations English will translate it more naturally as to leave.

In this sentence, because someone is being told to message first, the meaning is naturally: message me before you leave.

So the Persian says before going, but English often prefers before leaving here.

Persian often leaves the subject understood from context.

Because the main verb is an imperative directed at you:

• پیام بده = message me

the listener naturally understands that رفتن also refers to your going/leaving.

If you want to make it more explicit, Persian could say:

• قبل از رفتنت = before your leaving / before you leave
• قبل از این‌که بری = before you go

So the original sentence is natural, but slightly less explicit than those alternatives.

Yes. This is because پیام دادن is a compound verb in Persian.

• پیام = message
• دادن = to give

Together, پیام دادن means to message, to send a message, or to text.

So:

• پیام بده = message! / send a message!

This is very common in Persian, where a noun combines with a light verb such as کردن, دادن, or زدن.

به marks the recipient: to someone.

So:

• به من پیام بده = send a message to me / message me

Word by word:

• به = to
• من = me
• پیام بده = send a message

In English we often just say message me, but Persian commonly keeps the equivalent of to me.

Here تا means so that.

It connects the first action to its purpose:

• ... پیام بده تا ... = message me so that ...

So the whole idea is: Message me before leaving so that I can wait for you / be expecting you.

In other contexts, تا can also mean until, so learners often find it tricky. Here it is definitely the so that meaning.

Because after تا meaning so that, Persian usually uses the subjunctive.

• باشم is the present subjunctive of بودن for I
• باشم = that I be / so that I may be

So:

• تا منتظر تو باشم = so that I can be waiting for you / so that I can wait for you

This is a very common pattern:

• زود بیا تا با هم برویم = come early so that we can go together
• بگو تا بفهمم = say it so that I understand

In Persian, منتظر بودن is the standard expression for to wait or to be waiting.

So:

• منتظر = waiting / expectant
• بودن = to be

Together:

• منتظر بودن = to wait, to be waiting

That is why Persian says:

• منتظر تو باشم = I be waiting for you

English uses a simple verb (wait), but Persian often uses an adjective plus بودن.

Yes, absolutely.

Both are correct:

• منتظر تو باشم
• منتظرت باشم

The second one uses the attached pronoun -ت = your / you in this kind of construction.

So:

• منتظر تو = waiting for you
• منتظرت = waiting for you

منتظرت باشم is often a little more natural and compact in everyday speech.

Because the sentence is informal singular.

• تو = you (informal singular)
• بده = give/send/message (informal singular imperative)

If you want to say it politely or formally, you would use:

• حتما قبل از رفتن به من پیام بدهید تا منتظر شما باشم.

So the original sentence sounds like you are speaking to a friend, family member, partner, or someone you know well.

Yes, it is natural. A native speaker might also say a few close variants, such as:

• حتما قبل از رفتن به من پیام بده تا منتظرت باشم.
• حتما قبل از این‌که بری به من پیام بده تا منتظرت باشم.
• قبل از رفتنت حتما به من پیام بده تا منتظرت باشم.

These all mean roughly the same thing. The differences are mainly about style and how explicit the sentence is.

The original sentence is perfectly understandable and natural, especially in conversation.