With your OPT STEM expiring in Feb. 2016 and with your CN of AS3xxx (which I'm treating as closer to 4000, than 3001 - not revealing the next digit after 3 makes it hard to do a better job of guesstimating), opting to go AOS may not quite be a good idea. You could be out of status by the time your CN becomes current, and even if your CN becomes current in January for instance, it's still a dangerous gamble to take attending the interview when your current status has expired.
Of course you could argue about the possibility of early filing, assuming your CN becomes current on Feb. 1st, you could submit your I-485 package from Dec based on the early filing memo. However if your FO decides to deny your petition simply because they're not willing to recognize the early filing memo directive (or they're not aware of its existence), you will no longer be in a valid status by the time the denial comes through, which means you can no longer refile the petition from the U.S.