ed-j

I'm sharing our story just to give you some idea of the process you are considering. Hopefully it will help in your thought process.
My husband and I had to reschedule his I485 interview because it was scheduled when I was scheduled for a business trip. We requested the reschedule by phone the day after we received the letter. The lady seemed helpful, and a week later we received a denial of reschedule letter, which said they'd be happy to reconsider if we mailed in proof of the reasons we'd provided on the phone. The day after that we mailed off my itinerary and a letter from my boss about the already expended business costs etc. Two weeks later (and 2 weeks before I was supposed to leave) we received a letter saying our interview had been cancelled and any information about a new date would be sent later. So, that was about a 3 week process just to get the interview cancelled. And we always said "reschedule" so we were at first scared by "cancelled". Apparently USCIS doesn't actually have "reschedule" in its vocabulary. Just "schedule", "cancel" and "schedule".
For the next 2-3 months, we called USCIS about once a month to make sure we were still in the system and kept getting surprised responses that we hadn't been re-scheduled yet. Eventually, we brought in our state representatives office, who finally told us that by asking to reschedule, we had been put at the back of the line. Shortly after that we did receive the new interview date... original date had been March and our actual interview was August.
So, expect the process to be slow, and with no information in the interim. Also, get on the reschedule request like yesterday or they may not get the cancellation processed before your interview date. And know that you're stepping to the end of the line, the new interview likely won't be anytime soon once you return.
Our story did end fine. He got the green card also in August, we were approved right away once we had that little chat with the officer. It just tried our patience waiting.