As long as your bio page has no rips or smudges, your good to go. Girlfriend washed min and the stamps were all over the place some missing, some went through to the other page. As soon as you put your fingers on the scanner at border control on the way out, your visa info will pop up on the screen for the immigration officer
1 month, 2 months, 3 months doesn't matter. They want you to come back to Thailand and spend money after your class for the next 5 years without having to worry about vusas