The guidelines that my company (Exel) have given us is that any time above 5 minutes, if qualifying, can be claimed as a period of availability. Now on multi drop you might for example get to a delivery point and be told by the person recieving the goods that they will be 10 minutes while they clear space, find help, get keys etc, etc and that 10 minutes can be called a PoA. Likewise if your delivery access is blocked for a time that can be identified that can also be called a PoA.
I’d put the caveat that this is what Exel are telling us at our depot after FTA guidance, and we don’t do multi drop in the traditional understanding, so your company may be using different guidance. Best ask.