I actually tried it and it went fine.

What happened was I had booked my ticket to nepal for a month, took a month long vacation and everything was all set and 2 wks before my vacation I get the letter for Fingerprinting and it fell smack in the middle of my planned trip!

I conferred my lawyer and he said I should postpone my trip. I was just not ready to go over the whole hassle of planning the trip again so I just decided to show up for the fingerprinting even thought it was few weeks away even though my laywer said not to.

I showed up and they fingerprinted me and never questions about the scheduled date why or why not, and I was all set.

I'm not sure how it will work out for you but who knows it might.