I can't remember exactly but think it was about 11ish and that was on a Tuesday. Just make sure you get your photo beforehand as it's a bit of a walk from the office to the nearest photo place
I got mine extended last week in the Patong office and I was literally in and out of there in 15 minutes. I don't know if it's always like that as that was the first one I've done but I was surprised how quick it was
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