How do I trigger effects at a specific time during playback?

I have a project setup with multiple stems and a click track playing in Playback. I'd like to find a way to automatically trigger a mute/unmute of a bus, or turn on/off an effect at a specific point during playback.

Ex: Chorus starts, turn on delay. Chorus ends, turn off delay.

I thought I could export a .mid file from Logic (where the track plays a MIDI note at a designated time to use as a trigger) and import it into the Playback tool in Mainstage, but when I try importing it the file is greyed out.

Is there not a way to time effects to automatically turn on and off?