I'm going to be getting my 60 day tourist visa from the US before travelling. I have read that it can be extended 30 days for a total of 90 days at any time without losing days.

My main question , I'm going to be moving about, different hotels, maybe a long term rental mixed in. Does the immigration check for TM30 from the current hotel need to be showing dates for my entire stay. Since I only plan to stay at the first hotel for 2 days?

Or will it pass the check as long as the current hotel filed the TM30 for my 2 day stay when I go to Jomtien for extension? Hopefully that was all clear

The later. Check in Jomtien. Tell/ask staff that you want tm30 filed. Also ask for printout. (you won't need it but won't hurt)

Attend imm for extension