This might have time save potential. Important to note that you cannot drop down before both explosions finish. If you do, and the mother's shield is up, it won't do damage. You might be able to time it so that you can drop down and have it open up in time for the second explosion to hit, though.

Also good to practice the throw, as it's a bit difficult.

Update: This is fast. Can't say for sure just how fast it can be, but I got a 3 second gold the first time I tried it in a run. If you get the pitcher perk while waiting for the boss door to open, I imagine you wouldn't lose any time to getting the perk, since you're just waiting there anyway.