the pregnyl booster shots are generally about 1500 where the trigger is 5000 to 10000 - so it doesn't take as long to leave your system - rule of thumb from what i recall is about 4 days from the second booster it should be out of your system

if you're a compulsive POASer - you could always test each day following booster til you get a negative so you know it's out of your system, then start your testing for BFP after that!

good luck