At what levels can I expand my Cafe World, or is it based on neighbors?

Cafe World expansions are available based on your neighbor count. Here is the full schedule as released in the game so far:

Quaint Cafe - 8 x 9 - 500 coins (2CW$) - no neighbors required
Corner Cafe - 9 x 11 - 5000 coins (25CW$) - 2 neighbors required
Family Cafe - 10 x 12 - 50000 coins (30CW$) - 4 neighbors required
Plentiful Cafe - 12 x 13 - 125000 coins (35CW$) - 8 neighbors required