My Discover balance reports on the 9th of each month. Last week, someone decided to buy some expensive tires online, using my Discover card. God knows how they got the account number. Discover rejected the charge and sent an email to me. After I called them, they shut the card down and FedExed a new one to me (with a new number, of course).
Today, I got an email from Experian that my Discover balance had reported as increasing by $638. A CSR explained to me that when a card is shut down and a new number issued, there is an immediate report to the CRAs. If I'd known that when I had spoken to the CSR about the fraudulent charge, I could have made a payment then that would have been reflected on the off-cycle report to the CRAs.
Allowing $600 to report is not a big deal. Its actually good to let a balance report once inawhile as upon manual review by an UW they can see you have used a card whereas a steady stream of 0's shows them nothing, imo of course.