Indy field office
Sorry for the delay in answering your questions.
I did not make an appointment for getting the FP done early. I went in the INS field office to obtain an EAD and to apply for AP. In May 02 they still approved and issued EAD's for employment based I485 applicants on a walk-in same-day basis. Arriving there at 8:30 am, I took my number and waited my turn. When called (after about 2 hours), I gave them all the documents for the EAD and AP applications. I also showed them the fingerprinting notice and politely asked whether I could take the fingerprints early so that I would not have to make the drive to Indy a second time. They agreed, and I had to wait another hour or so to get my EAD done and get fingerprinted. The AP came one month later by mail.
I suggest you go to fingerprinting late within the timeframe stated on your fingerprinting notice.
When you get to the Indy field office, plan to arrive early, shortly before the time when they will open. You can park for free on the street one block west of the INS office, or you can use the pay-parking-lot ($2 for the day). If you have an appointment letter (eg your fingerprinting notice) you do not need to take a number. When they open the doors, someone will come and ask people with appointment letters to come forward. They will collect all the letters and then call you.
If you do not have an appointment you will have to take a number and wait your turn. Having done this procedure three times now, I can tell you that it take about 2 hours, regardless when you showed up. Some people chose to be there at 6 am (or some other ungodly hour) and ended up standing in the lobby, wating fir the doors to open. If you show up at 8, you'll wait two hours in the waiting room, where at least you can sit.
Don't bring anything that could be construed as a weapon - the security will tell you to put it back into your vehicle. (This includes Gerber tools, as I found out).
Lastly, bring something to read, or to knit, or to otherwise entertain yourself, otherwise enjoy watching other people's children run, jump, scream and cry.
Have fun...
Mark