How and When do Ocelotes spawn? Minecraft (1.12.1)

Ocelots spawn in jungles biomes on both grass blocks and leaf blocks. If they don't spawn, you should try to kill all other animals. The game has a mob cap which prevents more mobs from spawning when this cap is reached. To get more animals spawning, make sure that both your jungle and your world spawn are cleared from any animals and you should see ocelots and parrots spawn in your jungle.