How long of time intervals should I do while using the Ab Lounge?

[This gum is fancy]

I think, but I'm not positive, that when I saw the informercial once, they said to use it like, 4 minutes a day, and you will start to see results. I've been doing it for like 5 or so minutes a day for maybe a couple weeks. And I'm seeing a whole bunch of nothing. I see or hear people doing it for 20 minutes at a time, which if I did that I would probably get sick because of all the back and forth motion. Whats a good amount of time to use it?