Thanks very much Rebecca for a most informative response.
I have one more question I'd like to ask if I may: does compost have such a thing as a shelf life? I mean does it go rancid, become unusable or lose its potency in some way after a certain length of time had passed, or does it last forever?
I can hear you all laughing....but I did wonder and want to be sure

Wouldn't want to bag it up and stash it away somewhere for another season only to find I'd wasted it by not using it soon enough.