They should be turned weekly but they don't get that much attention unless I have gardening apprentices here.
I added some more info to the previous post you may want to look at.
Typically how long does it take for it to be ready to use?
It depends on 4 factors
1 the kind of material you put in
2. The ambient temp
3. The ventilation =AKA how many times you turn them
4. The humidity in the pile