grass cuttings how do i know

currently i have a large pile of grass cuttings and other waste veg matter rotting away,
how do i know when it is suitable to be used on my plot? can i use it as a fertiliser and just dig it in?
am a noobie

and thats it no need to dig in?

You can use it in the bottom of a bean trench for next year or leave it over the soil surface. The earthworm activity will be slowing down shortly but I spread my sheep manure/bedding which has been in a pile over summer, so is only partially rotted down, on my raised beds and garden borders. In the spring it is amazing how friable it has got and you can leave it on the surface or dig it in when preparing your beds.