CRAs have 30 days (and up to 15 days beyond if info came in late from OC) to verify that whatever is reporting is accurate. If it cannot be verified or updates, it must be deleted off your reports (assuming you disputed on all 3).
CAs, with regards to DV, have no time limit at all to verify the info. They can take their sweet time. However, during the time they take to verify, the CA cannot engage in collection activities, like calls, etc.
Ideally, you want to dispute the CRA at the same time as the DV.
There is also debate (in my mind anyway) on the issue of DV. As per the FDCPA, you may DV a CA within the first 30 days of initial communication from a CA. This is typically the letter you get saying you have 30 days and so on and so forth, or the dunning letter. I'd argue, based on what the FDCPA says, they you can't DV after the first 30 days. On the flip side, an argument can be made that a CA wouldn't have any record at all of when you received that first letter. Or if you moved after the collection, how would you get any written notice. As a side note, I've DVed after the first 30 days and have been successful. Much of the time a CA doesn't understand the law anyway.