Trigger action during particular point in timeline?

I tried having elements appear further down the timeline that had a state change and tried to trigger other state changes based on it but so far, nothing.

Can you give an example? What are you trying to trigger? It is possible to have objects appear off the workspace that trigger different events, but it might depend on what you are trying to trigger.

I'm just trying to trigger an event at a particular point in time on the timeline. Specifically, I'm trying to get a button to change state in synch with the audio, but not at beginning or end.

this is really basic, but the boxes on the left trigger the button to change state along to the music

Thanks for the demo. This is exactly what I was trying to do BUT I added one layer of complexity that caused it to break. An object will fire an event (trigger) when IT'S timeline starts, not just the main timeline. HOWEVER, I was adding one extra layer that Storyline's back-end processing doesn't seem to like. I tend to use a lot of variables and when the timeline started, I was adjusting a variable and was anticipating the other object (the button in your case) to listen for that variable to be adjusted and make it's own adjustment at that point BUT that never happened. It probably has something to do with when the variables are changed in relation to the timeline or chain of events.

My main suggestion is NOT to "daisy chain" events together and go the direct route if you want to minimize your troubleshooting. For example, a picture changes state and when it does a variable is changed (false>true) and a button is listening for that variable to change and then it changes it's own state. DON'T DO THAT! Go the direct route! When the picture changes state have the button change it's state too! Skip the variable middle-man.