No, the Visa starts on the date it was issued, not when you arrive in Thailand. I know this to be true because my first 90 day visa was issued about a week before I arrived in Thailand and Immigration only gave me 90 days from the issue date. On the other hand, if you arrive on a 60 day tourist stay then it starts on the day of arrival.
Iām currently in Vietnam visiting and I have been thinking about going to Malaysia again (my last visit was in April 2025 for a week). I am thinking about going back for a month or more. I know I can get 90 days. Maybe that will give me time to figure this out.