Here's a link with some additional details. I also saw somewhere else that the time restriction is to be implemented Sep. 4, 2023, but don't hold me to that. https://community.ricksteves.com/travel-forum/greece/new-rules-for-acropolis-tickets
"Combined tickets do not have time slot restrictions implemented yet. You are therefore able to visit the Acropolis while your ticket is valid at the time of your preference".