Since she's such a young kitten, let her eat as much as she wants until she's a little older. Then it's best to do timed, measured feedings throughout the day. (If you're worried about when you go to work, give her a bigger meal before you leave.)
Some cats can regulate what they eat when free fed. My cat, Elly, is like this. Punky would turn into a bowling ball with legs if I free fed her, so it's not a good solution in my household.