How many pizzas should we order?

We are having a wedding in a couple weeks. Me, being the great and generous groom have taken the task of ordering the 'late night snack.' We have 147 people attending, we are eating dinner at 7:30, and have the space and open bar till midnight. We are thinking about ordering Papa Johns Pizza and having a scheduled delivery of like 11pm. How many Pizzas do you all think i should order? A lot of the older folks will probably be gone, so I was thinking like 10-15, thoughts?