When purchasing CTO models from at least some 3rd parties (e.g., Amazon Prime), the warranty begins when the product was originally shipped to the 3rd party, not when it was shipped or received by the end-user, which could be months later. (Or years later for out-dated models.) If buying CTO from a 3rd party, be sure to find out when the warranty begins or began. If you can get the serial number of an already-built device, you can look up the warranty yourself on apple.com
Apple will fix their records to reflect the actual purchase date if the owner submits proof of purchase. I've had to do it with an Amazon purchase.
As consumers, the retail purchase dates takes precedence, both in usual practice and under merchantability laws, not the wholesale date, unless the item was purchased under special conditions ("as is"; "used") or with other disclaimers.
While refurbs are an attractive option, they can't be automatically assumed to be the the best option. It's best to shop around first.
As I look at what I believe to the the base 15" MBP now (2.2/16/256), it's $200 off retail, $2199 at B&H.
The Apple refurb is $2039, and in any state in which Apple operates, and charges sales tax (almost all of them) the cost is in the same ballpark.
Another factor, for those who have credit cards that offer extended warranty coverage of their own, is that some of them have terms that may exclude refurbished products. The better programs will not only extend warranties, but can be stacked with AppleCare for even lengthier extended coverage beyond three years. Check the fine print.