Implantation bleeds can happen anytime after ovulation (it can happen on the day of implantation or much later) - it does depend a bit on when implantation takes place. Implantation can happen usually between 6 to 10 days after ovulation, though having said that I had an implantation bleed 4 DPO this time.

If you are bleeding on CD14 and CD15, could it be related to ovulation?