There really isn’t enough here to provide concrete advice. It’s not even clear what language you are using and whether this is in a text file or in the UI.
There are several irrigation tutorials on the forum including Design Pattern: Cascading Timers. Additional useful tutorials include Design Pattern: Associated Items and Design Pattern: Gate Keeper.
If you use JS Scripting, there’s a library you can install for Gatekeeper which makes implementing this really simple.