it took a few weeks for there to be 9 villagers in my town. The only way to get a 10th villager is by street pass, adopting, visiting a town or having a guest over in your town who has a "voided" villager ready, or inviting a villager via Wisp or if a villager is camping in your tent town project (the 3x3 tent, not the Harvey Campground)
6th villager will set up their plot the next day after you've created your town.
7th villager plot will appear two days after the 6th
8th villager plot will also appear two days after the 7th
9th villager plot isn't fixed. It may appear two days after the 8th or can take long up to a week.