Implantation bleeding?

I have no idea what my cycle looks like since I've stopped taking birth control and am still figuring things out. I put 90 days into Glow because I got my period in July, October, and February. If that's accurate, I should be getting my period in about 5 days, and my fertile window was about a week and a half ago. ANYWHO. Yesterday I had some light brown spotting. I put in a light tampon and 8 hours later there wasn't much of anything. There was a little more through the night, but not my regular "period" type of flow. Does this sound like it could be implantation bleeding or just my body figuring things out without birth control? And how long after this potential implantation bleeding should I take a test?!