I couldn't find a definitive answer for this, but what I did find suggests that there is no definitive answer - it depends.
From this site (which sells legal DIY products, but also contains articles by member lawyers)
Advance Parole is normally granted for multiple entries into the U.S.
and for the time period required to complete the adjustment of status
application, not to exceed one year. This isn’t set out in the law
anywhere; it’s a matter of USCIS policy.
So, theoretically, you could stay out of the U.S. for up to a year,
making sure to return before the expiration date on your document.
However, the author goes on to warn:
Just be careful about what you might miss while you’re away. USCIS
will call you in for biometrics (fingerprint and photo) within a few
months after you submit the adjustment application, and for an
interview at a local office several weeks after that (the exact timing
depends on how backed up with other applications it is).
If you miss one of these appointments without asking for a
postponement, you could put your entire application at risk. And even
postponing such appointments can delay the process by a long time.
The answer to your question, then, is to apply for Advance Parole, and the response will set the time you can be away. You will probably be fine to travel for the period you're planning, but be prepared to change your plans if necessary, and be wary of the caveats above.