If it only takes 5 min, then it's too loose!
The easiest way to get it on is to walk up to the power rack with a bar at chest level. Have someone wrap your front straps around the bar a couple of times and then have them hold on. Then you just sit into the suit with your body weight. Turn around & do the same with the back straps and you should be able to get seated in them.
Is your shirt open back?