How do I know when it's time to use compost?

when it doesn't stink. and yes do keep a new pile going

This article may be helpful: https://www.craftylittlegnome.com/when-is-homemade-compost-ready/

It smells like dirt without chunks left. Go to the bottom of your oldest pile...you’ll find it there.

Looks like dirt, no stuff in it that isn't broken down.

Hello, hope this helps you out. To maintain healthy soil, you should add a thick layer of compost - at least 2-3" - every year. If you're using homemade compost, it's best to add it in early fall so that by spring, it will have broken down and worked itself into the soil. Adding a thick layer of compost in the fall also helps reduce weeds.