Hammer - How to delay trigger_push?

I’m editing a map with tornadoes in it by request of its developer. I am not very good at hammer and I just have one question.
I need to delay the trigger_push so it doesn’t take effect until the particle is shown to be on the ground, is this possible, and if so, how?
I can also use a way to delay the speed of the func_tracktrain, which the particles/trigger_push ride on, could I possibly make it slow, then make it automatically change the speed after a set period? If so, how?

Gotta use a separate trigger_multiple