I am going to WDW for a conference in February and was able to purchase after 5:00 entry tickets. I may be able to get to the gates by 4:30 each day though. Has anyone successfully been able to use the 5:00 tickets a half hour early or is it strict to the 5:00 time?
pretty strict, in my experience. I think maybe 10 min early? but as always, it’s at the discretion of the CM, so YMMV 
good luck!