FYI Jomtien Immigration.
I have just done a 90 day report. The TM30 office is now manned up with 3 desks and it's packed out. I would say if you've not done a TM30, go and do it before you need to do your extension etc unless you want a delay.
They confirmed they expect a TM30 report within 24 hrs of returning, no matter what visa or extension your on, if you spend time out of the country AND/OR out of Chonburi province.
Don't shoot the messenger.