@Jon *******
.. before you loose your track in the forest of comments above.
May we know on what kind of visa you be entering Thailand?
* 60day pre-payed Tourist, extendable in country with 30days
* no visa, but free exemption stamp on arrival. atm 45 days (15 Quarantine + the normal 30). extendable in country with 30days
* STV (special tourist visa) 90 days, extendable in country with 2x90days
The whatever time you get granted (30-60-90) always starts when you arrive and get stamped in.
Visa stickers have an expiry date. Which is 90 days from application granted. This date is printed on the visa and is the last date your visa is valid and you can enter Thailand or extend your stay incountry at immigration on that visa.
There is no such thing as 90 day reports for tourists. This is for Bussiness, Marriage or Retirement visas etc that have a validity of a year.