Set variables on load/start of prototype?

I’m looking for a way to set a variable on prototype start or onLoad? I know I can set the default value but there are some cases where I would like to add some logic onStart or onLoad. Does this functionality exist? Am I missing something?

There are no interactions/conditionals yet for onStart or onLoad, so one way I’ve gone about setting variables/running conditionals at the start of a prototype is using a starter frame, and when a user clicks “start” I set all the variables I need.

You can see an example of this approach in my “Dropdowns: Dual Filtering” community file:

I usually set an initial variable with the action “After delay” and set the timing to “1ms”.