Compost piles are usually ready to use after around three months as long as you keep the temperature of the compost between 130 F to 170 F.
The hotter the temperature of the compost pile the sooner the compost will be ready and sometimes compost may be ready in as little as 1 month.
Be sure to turn the compost often and keep the temperature up of the compost and it will be ready at least in 3 months but sometimes 4 months.