I can understand why being late is a problem. One of my jobs is scooping ice cream, and we never know what business will be like for the day, so I make it a habit to try and be early (5 or 10 minutes, occasionally more) so that there is never a shortage of help if we get hit really hard. Applying this to the starting issue, I second the idea of peer pressure. Have the people working with him explain to him how hard it is to keep up on work when he's not helping.
