So, here's some the reasons the time line shifted, IMHO:
1) After Kaylee's sister Alivea got K's call records the day/days after the murders, the time had to be moved to after 3 because of documentation of Kaylee calling and texting her ex Jack many times between 2 and 2:56, with Maddie calling/texting Jack as well during that time frame--unless we are now believing that the killer used Maddie and Kaylee's phones to make those calls.
2) As for 4, that would come from the Door Dash delivery. Obviously, we don't have LE confirmation that the Door Dash person SAW and delivered the meal to Xana. But LE did confirm in the PCA that they had talked to the DD driver and confirmed the time of delivery. So unless the killer actually killed everyone between 3 (after Kaylee's last call to Jack) and 3:30 (which would be about the latest time time for JIB to receive and make order, DD driver to go pick it up and then drive to 1122 King and arrive by shortly after 4) and then the killer placed the order at 3:30 with the thought of throwing off the timeline and put in the directions that the order was to just be dropped at the door.....then there isn't much reason to question the after 4 am timeline. I suppose the killer could have done some of the murders between 3 and 3:30, paused to set up the JIB order, then gone and killed the other 2...but that's cutting it close to then get out before the JIB order arrives around 4.
3) So, the JIB bag that is seen in the kitchen photo might not be the JIB order from that night. But if you are suggesting that the DD driver just dropped off the order without seeing Xana, and that allows for everyone to be killed before 4.....then you would expect that the JIB order would still be outside--and noted in the PCA--and found there the next morning.