It takes a good long while for the offers to dry up after opting-out. And in the same manner, once you opt back in, it can easily take four weeks or so to get your name and number scrawled on the creditors' bathroom walls.
Opting in or out does absolutely nothing for your scores, other than reducing the temptation to apply for credit, and thereby getting the various dings that come with new credit. Your opt-in/out status isn't factored into your scores.
As impulse control has always been my weak point, I opted out for a long time while I did my research here and worked and waited to get my scores and reports where I wanted them. I opted back in a couple of months before my app-o-rama, so that I could use the online pre-approval sites to see where I stood, and look at the offers I got in the mail to guess how marketable I was. I'm still opted in, because although I am still a completely undisciplined dingbat in other areas, when it comes to credit, I'm now pretty ruthless.
* 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