First, any account that you have paid on must report the new balance/ activity to the CRA's (credit bureaus.) Then the CRA's have to post the new balance/ activity. They usually do this pretty promptly.
You can call your CCC (credit card companies) and ask them what date they report on. Frequently, but certainly not always, they report on your statement date. The statement date usually comes about 3 -3 1/2 weeks before your due date. As for collections, they are supposed to update pretty soon after you pay.
Paying off collections doesn't particularly help your score, which is ridiculous but true. Did you by any chance read here first about PFD's (pay for delete)? If you can get a creditor to agree in writing to PFD, they will remove the collection from your credit reports. Otherwise, it stays there, but now showing as paid (or whatever you might have negotiated.)
* 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