Implantation Bleeding

I got my Mirena IUD removed on July 20th and my doc said we could immediately start TTC. We literally started that day. A couple days later I had cramps and spotted very lightly for a day (FYI I haven’t had a period for about 3 years bc of the IUD) We has sex pretty much every day for over a week then a couple days ago I started having mild cramps and yesterday I started to spot very lightly and it was very dark. It has now completely stopped. Could this be implantation and how long should I wait to test?