How long can autos flower apart from another, if planted at the same time, and same strain? One of my girls is flowering and the other not?

Usually the same genetics should behave much in the same way, you’re right about that. Even with the “hard” transplant , it should recover much in the same time. What I suggest is try to use molasses or flowering nutrients to try “trigger” flowering. If that doesn’t work maybe you even have unstable genetics , you can try to do a 12/12 light schedule , in case it’s not an auto (happens often actually when the breeder makes a mistake) . Hopefully some patience will work, but it looks like you maybe got unlucky actually. Just call the breeder when you’re absolutely sure and show him the diary usually they will do something that’s fair for you. hope this helps ! 🚀