Natalie,
I believe that yes it's possible. Lots of people would say no because HCG is only released after implantation, which usually happens 6-10DPO, but I've read there's either a form of HCG or a different hormone that is released after fertilization but before implantation, so this might cause symptoms too..
Last cycle I started getting my symptoms at 6DPO (butterflies in tummy, left boob hurting), and didn't get my BFP until 10DPO (I tested on 9DPO too).
So I hope these are great signs for you!!