Congratulations! It depends on which immigration office and the mood of immigration officer. I was doing Non-O based on marriage fourth year in row and it was the first year when all documentation was correct (Imm. Div. 1). In the previous years it was demonstration of their imagination what else to invent to annoy us... So this year we took everything, I even took results of my latest medical check-up, to avoid going there again...
Yes, you can do it anytime, but on the airport (at least Suvarnabhumi) it's really smooth, just 10 minutes waiting. Have one photo with you and cash to pay.
Barry Burbridge which Immigration Office? one year ago I was applying with 400k for the first time in Chaengwattana, when collecting stamp they asked me for bank book, I didn't have (nobody told me I should), so they said to bring next year