The sooner the better, the payoff will be to their advantage. Trust me. My kids are 19 and 23, very mature, very responsible. Set an example for them and they will take the lead. They had "minor" responsibliites starting at 7 years old and have stepped up to the plate because the expectation was in place. Raise the bar high and they will respond.
Thank you for the comment - I suppose I always try to control the outcome to some degree... this time I'm just letting it go.