Thanks!
And nice! I really like it, too. It's been going strong for almost 4 years now, though I had to replace the switches on it last year.

I've been working them out for about 2.5 years now. But I've expanded and changed my leg routine over that time.

For the first 1.5 years, I simply did squats and lunges. Those two exercises alone were tough enough to destroy my entire glutes for a few days.
Squats would be 5 sets, 10 reps, with increasing weight each set. Lunges were 2 sets, 10 reps each leg. I normally hold dumbbells for those.

Eventually I tried/added straight legged deadlifts, booty band exercises, barbell pelvic thrusts, Bulgarian split Squats, etc. I don't do all those in a workout; that'd be too much. But those do provide a good variety. Hopefully this helps!