Creating spores using dust particles

I’m trying to create spores similar to what you see in Stranger Things. The problem I have is that the particles have a life time. They are born, they live, they die. In my case, I need to have the particles live forever and I want to stop the emission after a certain time, when I have enough. Even better would be to have, like in Maya, an initial state. It’s start with already the right amount of particles. So I’m looking for to have particle live forever and have an initial state if possible. Or maybe I can use a warmup to reach the amount needed?

Not sure how many you need but, sounds like you are wanting to spawn actors and not use particles for this.