Both my wife and I just walked-in (separate days) about 3 weeks ahead of our scheduled dates and they allowed
both of us to get early fingerprinting right there and then, and that could end up being the difference between us getting our cards or not, we'll see. However I think the follwing is important:
- go when the ASC is quiet. Avoid the mornings (esp. Saturdays) as the supervisor is less likely to accept walk-ins when it's busy. The first time we went together on a Sat. morning and the place was packed, so he gave us our marching orders. I decided to go back the next week on my own (lucky he did'nt remember me) on a Thurday afternoon at about 2.30 pm. There were only a few people there and I was done in 20 mins. My wife went to next week, same time and she was done in 10.
- have all you paperwork handy i.e. your letter, original conf. number and ID
- be prepared to tell a good story
and don't sound too desperate
- offer to come back the next day if they can't squeeze you in
I think going when it's quiet is the key. These are just my experiences, take them for what you will and good luck trying. I know it's a stressfull time for everyone.