People in this forum correctly recommend that you should enter the U.S. a week or more before AP expires. Do not wait for the last few days. Imagine your flight is postponed because of the weather, for example!
As for the duration of stay, there is no specific limit on how long you can stay outside the US (at least I have no knowledge
of such a limitation). However, since you are waiting for GC, the authorities assume that you are available in the U.S. for answering RFEs, doing FP or reporting for an interview as needed. BCIS normally gives you 80-90 days to provide answers. Cases may be denied if not answered in time.
Therefore, a sensible GC waiter who handles his own correspondence with BCIS should limit his stay out of the U.S.
to 2 months at the most and also have someone check his mail on a regular basis.
If the GC waiter has a decent lawyer, then there may be a way to stay out even more - but it is better to check it with the lawyer first.
I am no lawyer, so consult an expert lawyer before making a decision. This may have serious consequences.
(-)HR04
