It’s important to ask the farmer how long its been rotting for, ideally you want it to have been rotted down for at least a year.
Anything less than that could have a much higher concentration of nitrogen which can actually damage your soil.
If you do have the time and facilities to prep your soil now then I strongly suggest you do so, you’ll thank yourself as next year’s planting season comes around and you’ll have less work to do!
And let’s face it, after the colder months there are plenty of other garden jobs to be getting on with. The more you can do now, the better.