There is no window of taming to be honest. Really, once they're more than a few weeks old and have yet to be introduced to human hands, that's a missed window. However, most hamsters will tame down with lots of patience and persistence. I've only ever had one hamster who absolutely refused to do anything other than bite. Keep doing what you're doing now, but you can also try having your hand flat in the cage if she seems confident enough for that. Good luck, and if you ever have any other questions, please ask
