What is the time frame for implantation bleeding?

From day10 post sex: It takes the fertilized egg about 7 to 10 days to travel down the tubes and enter the uterus where normal implantation begins. From that point on the embryonic cells called the trophoblasts implant into the endometrium, invade, proliferate...and placentation starts. "Implantation bleeding" may be noted then but later on as the placenta grows and grows, intermittent may rarely occur still.