When buying your ticket, if it is not valid for all the days of the show, you must choose its validity date. Some events also have set access time slots, if so, you will need to choose one as well.
After selecting the type of ticket you will be allowed to choose its validity date and access time slot: 

Once the purchase is confirmed, in the ticket that you will receive by email (also available for download from the ticket purchase website) you will see the date of validity and the time slot if it exists: