I'd give it 3 or 4 weeks. Don't worry, I sent some GWs CMRRR before I knew any better, and I also sent a few really nasty form letters (found on "other" credit forums) to one creditor, before I found this forum and realized I should be sending sweet, apologetic GW letters instead! OOPS!
Don't fret, though. Most organizations are large enough, that if you tick one person off by sending the GW CMRRR, the next person to receive your next GW won't know anything about it... I send GWs to Cap1 for DH once a week, though. They're just SUCH a big place that it could take a lot longer before anyone starts recognizing his name & takes off the old lates just to stop the GWs from rolling in!