Treat it like part of your workout routine - don't just pick them up any old time or several times a day. Make sure your hands are warmed up and you don't overdo it, because you will injure your hands.
Also, you say you just ordered some No. 1's? If you haven't been training your grip, I think you'll be surprised how tough they are. The average guy who lifts weights usually can't close the No.1, and if he can, it's might be for just a couple reps.
I think Paul Black is probably much more knowledgeable and experienced than me, but I wouldn't advise training hard with them more than 3-4 times per week. And just 2-3 times may be best. (Sometimes it's nice to have more than one gripper so that light training can be done in between the more intense sessions, but that's not necessary.)
If you are serious and consistent, but don't see improvement, I'd advise doing less and not more. Just my thoughts from personal experience. (Also, your grip strength will be a good measure of whether you may be overdoing it with all of your training in general.)
