Pending AOS, possibly imminent approval, and change of DOs

[apviaaos]

AOS pending due to namecheck for two years. Just received a letter from the local office stating that "to continue processing your application, you must go to an INS application support center to have your biometrics and fingerprints taken." My initial biometrics/fingerprints expired about 5 months ago. At the local office case inquiry appointment at the time, I was told that I won't receive a new biometrics/fingerprint appointment letter until all of my security checks are cleared, which seems to be a regular procedure judging by other applicants' reports. It appears then that my namecheck has been cleared and that soon after I re-take my fingerprints this coming week I may get approval. Finally to my dilemma: I'll be moving to another area under a different DO early next month. Given that my approval may be imminent, I'm tempted to postpone reporting change of address to avoid the most likely lengthy transfer of files to another DO that is bound to protract my adjudication. Instead I may provide another address at my friend's residence in the area where my approval etc can be sent. Is this prudent and problematic? Formally, you are given 30 days to report change of address. What is the reasonable informal limit? Thanks