Hide object on main timeline

I have an object on a secondary timeline and set to hidden. I want an action to change this from hidden to visible. But when I go back to the Main timeline the object is visible? how do I make it hidden at the start on main timeline. Thanks

You first hide it on the main timeline. Then go to the other Timeline and set it up to become visible.

set a start keyframe which will pick up the current state and then set a new keyframe for the new state

In must cases you will always need to make sure that elements are set to the beginning state of what you want on the main timeline before you adjust them on another timeline.