I used to have problems getting my players to the game on time. They'd stop for snacks or something and be three, ten, fifteen minutes late. I prefer to have everyone there on time so no one is waiting on anyone else.
So to encourage punctuality, I started offering a chit good for one re-roll once during the game, usable in that session only. It's like a lesser version of luck. It's not much, but the players really enjoy it, so it gets players into seats on time.
I could just tally whether each player has used their re-roll or not during a session, but I find that giving them phyical chits helps them keep the option in mind better. For chits, I use pentagonal pieces from a Jovo construction toy set, which is a cool thing in its own way.