My 60 day TV ends this Saturday the 26th. I will go to Immigration for the 30 day 1900 baht extension but if I go in on Monday am I ok? No 2 day overstay? Or do I have to go in on Friday?

From past reports, you could go on Monday without problem. But, you can do it before the last day and not lose any days.

You can do it a week or two before, so today will be fine. The extension will start any way from the 26th, not from the day you apply.

Thank you. So I will go n tomorow then I think.