Learn Hardcore Chinese: Tā yǐjīng xíguàn měitiān zǎoshang liù diǎn qǐchuáng zuò zǎofàn. - She is already used to getting up at six every morning to make breakfast.

已经 emphasizes that a state has already been reached.
In this sentence, 她已经习惯…… means “she is already used to …”, stressing that the process of getting used to it is complete.

已经 does not always require 了.

With an action verb, you very often see both:
- 我已经吃了。= I’ve already eaten.
With a stative verb / adjective like 习惯, 喜欢, 清楚, etc., you can often drop 了:
- 她已经习惯每天早上六点起床。

Adding 了 here is also possible:

她已经习惯了每天早上六点起床做早饭。
This version makes the “change” or “completion” feeling a bit stronger, but both are natural.

Is 习惯 (xíguàn) here a verb or a noun? Why don’t we have 是 (shì) like in “She is used to …”?

In this sentence, 习惯 is used as a verb meaning “to be used to / to be accustomed to”.

Structure:

已经 + 习惯 + [action]
她已经习惯 每天早上六点起床做早饭。
= She is already used to getting up at six every morning to make breakfast.

No 是 is needed, because there is no linking structure like “A is B”.
You can also use 习惯 as a noun:

她有早起的习惯。= She has the habit of getting up early.

But in your sentence, it’s a verb taking the whole action phrase as its “object”.

How does the time phrase 每天早上六点 work? Why is the order “every day – morning – six o’clock”?

Chinese generally orders time expressions from larger to smaller units:

每天 – every day (biggest)
早上 – in the morning (smaller)
六点 – at six o’clock (smallest)

So 每天早上六点 literally stacks these: “every day, (in the) morning, (at) six o’clock”.

This is the normal order.
Reversing it, like 六点每天早上, is unnatural.

Where do time expressions usually go in a Chinese sentence? Could I move 每天早上六点 somewhere else?

A common word order pattern is:

Subject + (time) + (place) + (manner) + verb + object

So you get:

她已经习惯 每天早上六点 起床做早饭。

You can also say:

她 每天早上六点 已经习惯起床做早饭。 (understandable but less natural)
每天早上六点, 她已经习惯起床做早饭。 (time fronted for emphasis, sounds fine in speech/writing)

The most natural in everyday speech is close to the original: put 每天早上六点 right before the verb phrase it describes (起床).

Why is there no connector like “and” between 起床 (qǐchuáng) and 做早饭 (zuò zǎofàn)? Can I say 起床和做早饭?

Chinese often uses serial verbs: multiple actions are just placed one after another without a conjunction:

起床做早饭
literally: get up, make breakfast

Here it implies sequence: first she gets up, then she makes breakfast.

You can say 起床和做早饭, but that sounds more like listing two separate, equal actions in a neutral list (“getting up and making breakfast”), and is less natural in this “routine sequence” context.
For daily routines where one action follows another, the serial verb form 起床做早饭 sounds more natural.

What’s the difference between 起床 (qǐchuáng) and 起来 (qǐlái)?

起床 specifically means “to get out of bed” (to start the day).
- 我六点起床。= I get up at six (out of bed).
起来 is more general: “to get up / to stand up / to rise”, and is also used in many other patterns (directional complement, aspect complement, etc.).
- 他站起来。= He stood up.
- 吃起来很好吃。= (Once you start eating it,) it tastes good.

In your sentence we’re talking about leaving bed in the morning, so 起床 is the precise and natural verb.

Why is it 早上六点 (zǎoshang liù diǎn) and not 六点早上?

For time-of-day phrases, Chinese normally puts the time-of-day word first, then the clock time:

早上六点 – 6 a.m.
下午三点 – 3 p.m.
晚上八点 – 8 p.m.

So the pattern is:

[time of day] + [hour 点] (+ [minutes 分])

六点早上 is not the normal way to say “six in the morning” and sounds wrong.

What’s the difference between 点 (diǎn) and 点钟 (diǎnzhōng)? Could we say 早上六点钟 here?

点 = “o’clock” (very common in speech)
点钟 = “o’clock” (a bit more formal or explicit, often in more careful speech or writing)

You can say:

她已经习惯每天早上六点钟起床做早饭。

Both 六点 and 六点钟 are correct here.
In everyday conversation, people usually just say 点.

Can we omit 每天 (měitiān, every day) or 早上 (zǎoshang, morning)? How does that change the meaning?

Yes, you can omit them, but the meaning becomes less specific:

她已经习惯 每天六点 起床做早饭。
= She’s already used to getting up at six every day (but not necessarily only in the morning; context usually makes it clear it’s 6 a.m.).
她已经习惯 早上六点 起床做早饭。
= She’s already used to getting up at six in the morning (but doesn’t say it’s every day).

The original 每天早上六点 clearly says: every day, in the morning, at six o’clock.

Is it possible to say 她习惯了每天早上六点起床做早饭 instead of 她已经习惯……? What’s the difference?

Yes, both are natural:

她已经习惯每天早上六点起床做早饭。
她习惯了每天早上六点起床做早饭。

Both mean she has become used to it. Subtle differences:

已经习惯: focuses slightly more on the current state (“she is already used to it”).
习惯了 (verb + 了): emphasizes the change / completion of getting used to it (“she has gotten used to it now”).

In everyday conversation, they are very close in meaning and often interchangeable.

Why doesn’t Chinese mark tense like English “used to / got used to / is used to”? How is time expressed here?

Mandarin doesn’t have verb tense endings like English.
Time is usually expressed using:

Time words (每天, 早上六点, 昨天, 明年, etc.)
Aspect markers like 了, 过, 着
Adverbs like 已经, 正在, 还没

In this sentence:

已经 tells us the change happened before now.
习惯 as a stative verb shows her current state (“is used to”).
每天早上六点 locates the repeated action in time.

So the whole sentence is understood as a present state resulting from past experience, like English “She is already used to…”.

Is there any difference between 做早饭 (zuò zǎofàn) and 做早餐 (zuò zǎocān)?

Both mean “to make breakfast”, but:

早饭 is more colloquial / everyday.
早餐 is a bit more formal or used in written language, menus, hotels, etc.

In a daily-life routine sentence like this, 做早饭 sounds the most natural.
You could say:

她已经习惯每天早上六点起床做早餐。

and it would still be correct.