Creating a particle effect that fades in over time

Hello, I’m trying to set up a particle emitter for a smoke effect that gradually fades in when activated. At the moment I have a particle effect I found online, and when I activate it, it goes straight into full flow, producing loads of smoke. What settings should I be looking at the make it fade in over about 3 seconds, starting with no smoke particles and building up?

So far, I’ve trade changing the spawn rate by adding a curve that starts at 0,0 and goes to 3,3. I’ve also got a curve for “alpha over life” that does something similar. However, when I click “restart sim”, It doesn’t fade in or build up, the emitter just goes straight in to producing a constant amount of smoke particles.

I feel like I’m missing something fundamental. I want the particle effect to fade in slowly, and then continue emitting until it is deactivated. There must be a simple way to do this.

Also, my curve editor has no “x” axis values, unlike all the tutorials I can find. What am I missing?

Well, it turns out the problem was with the particle warm-up settings. I disabled the warm-up in the particle editor and now I’m getting the behavior I wanted.