Implantation and implantation bleeding occur on average about 9 days after ovulation (range between 6-12 days), which is about a week to a few days before your period would normally start. Spotting that occurs around a week after ovulation can be implantation bleeding; whereas spotting that occurs much later and a couple days before your period would normally start may not be. A normal menstrual cycle generally starts off light and then gets heavier.
What you may consider to be implantation spotting can sometimes be the sign of an early period and that means you are not pregnant. If this is the case, the spotting will pick up to heavier bleeding. If you have spotting right around the time your period would normally start, it can be more confusing. You will need to take the wait and see approach or take a pregnancy test to determine pregnancy.