I'm not a parent so of course I can speek authoratively on the subject .
Seriously I think you cant start young enough with kids who know about the truth (i.e. have been to the hall have relatives in the 'truth.)
A friend of mine who left says how his mom is pressuring him to read the book of bible stories to his kids and 'at least let her take them to the meetings.' We all know they will use the conditioning program to get the kids to believe that satan has gotten to mom and dad and how the kids need to make stand or some bullshit like that.
Its rough the thought you have to actively deprogram kids at such a young age but this cult has no sense of fair play. The last thing you want is a seed being planted in your children, because you wanted to spare them the truth about 'the truth.'