How long will it take credit card companies to lower their interest rate now that the Fed has lowered their's?

I know that credit card companies aren’t REQUIRED to lower theirs, but they usually do, right? So can I call my credit card company tomorrow and ask for a lower rate, or should I give them a week, or what? All I know is that about 6 months ago I called my credit card company [...] http://bit.ly/iLklqq