Question Timeline sync problem

I'm running into a problem in using Unity's timeline for animations. My editor runs at 15, max 35 fps.
When I create an animation from the timeline, let's say I define a cube appearing at 02 seconds.
Then I compile the app for iOS, when on the device I can get a much higher frame rate (capped at 60fps by scripting), so the cube appear smuch earlier than 2 seconds when the app is compiled and runs on the device.
The question is: how can the timeline be used to get a consistent behaviour between the editor and the app? It's pointless to have a time to define animations when these are later changed when the app is compiled for a device....

 

Timeline does not depend on frames, but depend on real time (Time.deltaTime). So if a cube appears at 2 sec in editor, it should also appear at 2 sec in iPhone, no matter the framerate. (there may be small error, 2.001 sec or something like that)