Not sure I understand your question.

How long it takes at the airport varies because it depends on how many people are working at the desk and how many are in the queue to get one. It has taken me 10 mins at DMK but it has taken me 30 mins as well. The last time I got it at Swampy, it took me 15 mins.

Robert, she was on extension of stay at previous school. It doesn't get automatically canceled from her leaving Thailand or finishing her contract as it happened to me.

Immigration will tell u if it's been canceled or not by your previous school.

No, not multiple entry. I wish u luck tomorrow. The thing with red tape at immigration is it depends who you get to process your paperwork. They all tell you different things at different times.

And yes, Robert is correct. I meant you need to cancel your extension of stay (what we referred to as 1 yr Non B).

Unfortunately leaving the country doesn't cancel the old one. I know because you guessed it, it happened to me. After I left my old job, I flew to Malaysia to get back in on a tourist exempt stamp. I thought everything was kosher when they granted me the 3 months. The 3 months was up so we went to apply for my 1 yr Non B and they discovered my previous Non B was never canceled. It makes no sense whatsoever, right? But you gotta remember, this is Thailand. Nothing ever makes sense.

This happened to me. You must get the old work permit and take it to Ministry of Labour office to cancel in person. By the way, you should cancel the previous Non B visa as well. If they didn't cancel your WP correctly, I am willing to wager they didn't properly cancel your visa as well. I had to do a costly visa run because I ran out of time on my 3 months Non B by the time it was discovered my previous school didn't cancel my visa.

I read in the Vietnam expat forum the other day a Belgian dude flew to Vietnam only to find out he needed a visa to get in. Oops.

You can't really rely on them. My previous school swore up and down they canceled everything after I left. Turned out, they canceled jack shit. It ended up costing me over 20,000 baht on visa runs and new paperwork before I got my new docs months later.

If you don't care to ever come back and work here again; no problem but I can testify from personal experience that it's a major pain in the ass if you want to return to work and don't cancel properly.