I''ve had non immigrant "O" and "B" on the same day - in fact within the hour. It depends on the consulate.
If you are Canadian my guess is that you don't need a visa and you will get on arrival by
AIR - 30 days permission to stay stamped on your passport at immigration......
If you enter or re-enter by LAND you'll receive a 15 day permission of stay. This is now allowed for any number od visits in one year.
Go to or phone your local consulate.
Yeah, I know that the VOA is available to me. I want to go with a visa though, because I won't have a return ticket and I want to be able to cross land boarders with out being limited to 15 days within Thailand.