Oh! In that case I think the easiest method would be to implement the delay in the heartbeat’s MetaSound.
The MetaSound would have both bip-bop sounds in it. The bip would play immediately on play, and then you can play the bop after adding a delay, the length of which you can modify using a float input for BPM.
This way you are only scheduling one sound to play using Quartz, and MetaSounds handles the rest.