Officially you are supposed to do your report... but...
Leaving the country within the 7 days after due date doesn't mean you don't have to do your report. At the border there will definitely no problem, the IOs there don't care about TM.47, not their business. But... it might be, that when you go for your next report after arrival, they see in the system that you skipped the last report. Now it depends a bit on the mood of the officer... maybe you're lucky and he ignore it, maybe he ask you for a little contribution to the Immigration piggybank (max. 2,000 Baht). But even if that happens, that's not a big drama... it doesn't give you a bad record... nothing to worry about.
So... long story short... if you have the time, go for the report before you leave. That takes you 100% on the safe side...
Anonymer Teilnehmer 905 You can report 14 days before due... if he did that his next report would be due on day 166, still 14 days on his entry stamp left. So... no overstay... but there's not enough information here to clear that.
Anonymer Teilnehmer 614 If he did his first report 14 days before due (for example), he would still have 14 days visa left before the next 90 day due date. So... no overstay at all. But... not enough infomation here to clear that.
Well... the intention of the form TM.47 (aka 90 day report) is that the Immigration can check if your registered address is still "up to date". So... it makes kind of sense that you have to report in the province where you live, no?