So the challenge for the administrators is to unwind all the positions before they start receiving oil or gold or whatever the traders have been dealing in.
The Fed has already gone so far with this program that it cannot unwind this huge portfolio of bonds without causing a sharp increase in interest rates and disruption in credit markets.
So if you bought 100 barrels of oil to be delivered in November then to unwind the position you have to sell someone 100 barrels of oil to be delivered in November.