I have done nothing but kits, so that may skew things, but I start the aging clock at the point where I could have bottled it according to the directions. If I chose to bulk age rather than bottle, it's still time counted as aging.
Example: I start a 6-week kit on June 1, rack to secondary on June 9, stabilize on June 25, could have bottled on July 15. Forever, that kit has a born-on date of July 15, even if I bottled it on Oct. 17 or whatever
Jim