Interrupting baby schedule for events

So some great and crappy news. MY BABY FIGURED OUT HOW TO NAP FOR LONGER THAN 30 MIN. I don’t even know how this happened but we’re doing great today all of the sudden!! Finally!! But here’s the catch... we have an engagement party tonight and it’s going to get SO messed up. The party is at 7.. usual bed time 9. It’s at the bride to be parents house and I don’t know them. I’m so happy my baby figured out how to nap but so sad it had to be today of all days!!!

How do you deal with these kind of interruptions??