Thank you for all the great suggestions. If we make it a game, it does mean that he is more likely to get ready and be on time. However, there are those nights when I am too exhausted to make it a game or I am getting ready myself to go somewhere that I can't do it.

I have also tried timing him, beat the clock, etc. which he does NOT like. He doesn't like the stress he feels when there is a clock involved, and a lot of times it ends up in tears and things taking longer.