If anything, I think that AmEx gets more antsy about what's going on with your other accounts. They will soft you very frequently at first, and if you suddenly have high balances or late payments on other cards, or go on an app spree, they will absolutely know about it.
So keep your nose clean on all your credit (a good idea, anyway) and give them time to get used to you. But definitely use the card --they like that. Just don't think about carrying balances and whatnot.
If you want to make payments on your balances before the first statement posts, you'll have to mail in a check, or initiate an online payment from your bank account, rather than on the AmEx site. But once the first statement posts, you can pay online from their site if you wish.
* Credit is a wonderful servant, but a terrible master. * Who's the boss --you or your credit?
FICO's: EQ 781 - TU 793 - EX 779 (from PSECU) - Done credit hunting; having fun with credit gardening. - EQ 590 on 5/14/2007