What date should I use for my 90-day report entry in Thailand: the last stamp date or the new visa activation date?

I’m sorry if this question has been asked before, I tried searching but couldn’t find the answer. I am going to attempt to submit my 90 day report online this time after I did my first one in person last time. My question is regarding the date of entry to Thailand. Am I correct in thinking this date should be the last date I was stamped into Thailand or the date I entered on the when the new visa was activated? Thank you.