Should I transfer my visa to a new passport before or after my 90-day report in Thailand?

If you can get the 90 day reporting online to go thru using the old passport that's fine too, it's just if you do it that way you're going to have to go do the NEXT 90 day report in person (so the new passport number can get into the 90 day reporting data base) where if you transfer the stamps and do a 90 day report in person now, there's a chance (slim as it may be) that you can use the online program after that.

I mean anyway you slice it you're gonna hafta do at least ONE 90 day report in person (or by mail, or send someone to do it) so you can get that new passport number in the 90 day reporting data base.

Umm how can a new passport arrive unexpectedly? :O Didn't you order a new one? ;)

Be that as it may

I'd go get the stamps transferred and THEN do a 90 day report on the new passport but that's just me