The first few Days they go nuts
The best time is to put the trap on midday when half the hive is outside and half in.
If it is not working 3 Days later it the wrong size of bees.
I am part of a group of 20 beekeepers that have put pollen traps on over 300 hives, only one had problems with FAT BIG bees that got stuck and wouldn't go through the pollen trap.
We use a trap that we empty every 5 Days with the vented collection basket under the hive. and alternate a left or right drone escape every 5 Days, after the first 5 Days of total close, only way in or out the pollen comb.