how to make a particle system store a bunch of particles and then let them all loose?

hi i want to make a particle system create lots of particles in a small circle as if storing them and then let them all loose after x amount of seconds or particles stored, right now ive just set up a particle system as a cone and created a single burst, i noticed that i can use the emit from property to emit from the volume shell or base shell and thought i could maybe create 2 particle systems one small one that creates the particles in a small area and then one that delivers the burst but being quite new to particle systems and unity in general i wondered if there is maybe a built in setting for this kind of thing that im missing any advice appreciated,

this effect would only be called once when a scene is loaded so i dont think memory consumption is an issue here

You could use the velocity over lifetime module. Use a curve for the velocity which is set to 0 and then increases after a certain period of time.