1st: A few days is the most likely thing. Probably two or three at most.

2nd: That would depend on the sire and what they're will is. An adult sire would be capable of manipulating their children into believing they were loyal for reasons beyond just the compulsion. And, even if they are turned by a neonate, that neonate's sire will have that sort of influence through the family line. So, really, the mind control aspects can vary.