Don't dare USCIS
mrconfused said:
When submitting all forms - i-130, 485, 131, EAD etc
once I have attended finger printing etc and im waiting for advanced parole to be approved is it possible to leave the country and have the AP sent out to me for my return?
mr. confused,
Don't you dare ever leave without an AP.

As Heretic mentioned, if you are called for an AOS interview before the AP is approved, then how are you planning to enter the country? I have seen situations where people assumed that USCIS will approve their AP and left the country, only to be called for interview and get their immigration issues complicated.

If you were an overstay of more than 6 months, then once you leave the country without an AP and are called for an interview, you will be banned for 10 yrs. So, stay put and get your AP before boarding the plane, or risk creating pain and sorrow for your spouse...
NB: Don't trust the bureaucracy of USCIS and expect everything to come when you expect it. People wait for AP for months, and sometimes they are never approved because they are called for an AOS interview and their GC are approved, then they lose the money they spend on the I-131 because once you have your GC, AP is useless...

In a ballshell, stay put and get your AP, or risk being held hostage by your own devices. Since you are in Vegas, processing times there tend to be much faster than national average, it is possible that your GC process could be done in less than 4 months. However, don't do anything which you will come to regret while outside the US...
