If he's deployed into active duty, he'd be eligible immediately. Otherwise he must complete a year of service.
How long ago did he get married?
He can get married again as soon he wants after the divorce, but sponsoring another spouse in the near future will be problematic.
EB3 ROW I-485 Approved: July 2007
USC: July 2013
I am a layman, not a lawyer. What I write here is not official or professional legal advice. In addition, my answers on this forum are specific to the scenarios discussed in each thread and should not be generalized to other situations.