Validate purchase date

Did you buy it from a third party or store? That means Apple has no record of your purchase. If you bought it from Apple, the purchase date would be registered automatically. You need to contact Apple to adjust the date if it is still covered by a warranty. You will need a receipt.

Yes, that should be ok as long as it is new? So, the problem is: Apple starts the warranty when they ship it so depending on how long it sat on the shelf there, it was "eating up" the warranty period.

In the US, you need to call Apple at 800-275-2273 and ask to be transferred to the Applecare division. Give them the information they need: serial number, place & date of purchase. I don't know what else they will need. You do need your purchase receipt which hopefully contains the serial number and ask them to change the purchase date to start the warranty. If it was not new, ask them what happens with the warranty.