I have had queries about why they only have 2 clowns, and do I really need to spend 900 Clams to get Pee Pants?
I have the answers confirmed by TinyCo!
You can only have 2 slury clowns and 3 grumpy clowns in your town at once.
The clowns will respawn every 4 hours so set your alarms and make sure you get those 10 clowns to finish Pt.1 of the quest!
I have other reports that some of the Clowns (as there are different types) will respawn every hour as well, but that is not from TinyCo.
UPDATED: I went into my game an hour later, and I did have a Clown so make sure you check in each hour!