So, you're a conditional LPR based upon marriage and you want to remove the conditions from your Green Card?
You file
form I-751 -
you, not your wife, are the petitioner.
The hearing on an I-751 petition can be rescheduled for good cause, but it is
not recommended that you attempt to do that. If you already know that your spouse is not in the country and may not be back even by the time of the interview, that's not the sort of emergency that is likely to result in rescheduling. You will not be able to move the interview to a foreign nation.
Once your petition is received and processed you would normally get a biometrics appointment in 30 - 60 days, and an interview @45 days after your biometrics appointment (give or take).