Don't wait until another time in your life to start your relationships with your kids. Start immediately. Your children will grow too quickly to wait for you to fit them in when time and life allow. You must set family as your main priority over work and sport and friends. If you don't start now, they may not be so responsive one day when it suits you.
If you constantly tell older kids not to do something, they will probably end up doing it. For instance, if you constantly tell them not to smoke, the focus on smoking and the rebelliousness in the child will most likely cause them to smoke. Worse then this is that they may hide it from you to avoid your disapproval. It is better to allow them to decide - they will anyway, but let them know how you feel, and encourage them not to hide things from you.