The CRAs report back the month and year only. So rather than an anniversary date, it is an anniversary month. The open is obvious. It is reported on the CR as the month and year opened.
So, if you have a CC that was reported as opened in 3/2008, then by 3/2009, it will be 12 months old and you may see a small increase. The time that updates this month is based on when your CC reports next (around your statement date). You can also cheat and see the info on your FICO reports. Look at the "Credit-At-A-Glance" page and you can see a line item for "Accounts opened in past year" or something like that. If that says 5, then you'd know that your CCs haven't updated yet.
ETA...creditaddict is faster and more concise.
Message Edited by llecs on 03-09-2009 01:00 PM