Controlling time on after effects sliders

Hi guys n gals,

I'm trying to create an essential graphics template for text within AE, the text needs to flicker on, hold, then flicker out. Quite simple (in theory) I'd like to control three variables with sliders. 

Time taken for text to appear.

Hold for a select amount of time.

Time taken for text to disappear.

I've figured out how to get the text to intro, but it keeps breaking thereafter.

Any help would be greatly appreciated