Why not keep it simple and insert a row at row 2 which would address your afore-posted "how do I get cells in columns B,C to follow thier corresponding dates".
A friendly tip, in your posts, your chances for getting a reply will increase if you don't use esoteric phrases. You have since explained "perpetual date" but now there's a new one, "fall off the worksheet" which you wrote within "numbers in column B,C to follow their corresponding date until they fall off the worksheet".
I'd say this to anyone, please understand I'm not nitpicking at you, just trying to help, those terms tend to stop people in their tracks and force an understanding of what you are talking about.
For example, you did not say what version of Excel you are using.
If
your version is 2007 or 2010
and
"fall off the worksheet" means you want to utilize all rows
then
that means, incredibly to some including me, that you are planning on over 1 million of these dates. The data would "fall off the worksheet" on March 4 of the year 4882. If you are using version 2003, the fall-off date would be "only" September 13 of the year 2190. A mere tick of the clock in geological terms, but for us living mortals, much longer past the date than we will be Excelling.