Previously, I have had my tm30 filed by owner 3-7 days after I arrived. I forgot how many day but it was for sure after 24hrs of my arrival. Went to apply for an extension a week later and I was fine. However you are supposed to have your tm30 filed within 24hrs of arrival but I feel that in Thailand lots of things are situational and the immigration officer you get. Some are nice and some are not.
all airport have ais. Just get it from there. Yes, it’s a bit more than if you go to an ais store at a mall or outside the airport. It’s probably $2-5usd more but it’s up to you if you wanna save for the inconvenience.