Implantation occurs when the fertilized egg implants inside the uterus to the lining of the uterus. This usually happens about 6-12 days after ovulation or about 2-7 days before you expect the next period.
Implantation bleeding as the first sign of implantation happens in up to 50% of pregnant women. It is completely normal to not have typical implantation bleeding, and probably the majority of pregnant women never have implantation bleeding.
The length of implantation bleeding is different from one woman to the other. And in general it only lasts a short time and it's only a few drops, much less than a menstrual period.
Typically, women notice a bit of spotting that lasts varying times. Some women may see implantation bleeding just once and other see spotting for a day or two. Any bleeding that's longer and heavier is unlikely to be implantation bleeding, though you will not know for sure until 6-12 days later when the pregnancy test is positive.