I agree with Cheezees in that rescheduling could be a challenge. Yes, you can TRY to reschedule but what if they don't get it in time? The concern I see is that if you MISS the biometrics appointment you are assumed to be abandoning your green card. I know it is not ideal but if I were you the only way I would feel OK would be to travel back before that date. Even if just one of you comes back early, whoever it is who has to DO the biometrics while the other stays behind in India.
The instructions for rescheduling say to send it to the address on the form and keep a copy of it for your records. I would hope that when they receive that they won't consider it to be an abandoned green card. But your timing is tight.
The phone number on the form is 1-800-375-5283.
