Main Menu - Start, Continue, Complete Triggers

At a previous company we had a template all set up that would change the button on the Main Menu from Start (no slides viewed) to Continue (at least one slide viewed), to Complete (all slides viewed).  Unfortunately I didn't copy the Variables and Triggers and am having a hard time recreating it.  

Here is what I remember, the Variables could be adjusted based on the number of slides in a scene.  The first Trigger on each slide added 1 to the slide counter.  The second Trigger said when the Slide Counter equaled the Slides Viewed the Start button would change to complete.  

I know they had a lot of custom slides so if there is an easier way to recreate this I would be happy to hear that too.  

Thank you