Ovulation question

Correct me if I'm wrong but cd 1 is the day after your period ends right? And if so is it normal to ovulate on cd 8? That seems really early to me. I use another app, period tracker and that's what it tells me. I just stopped taking my bc so obviously I haven't been ovulating but I'm trying to get an idea of when I will. My periods last 6 days normally and I usually have 21 days between my periods. I'm trying to get this all sorted out so we have a better chance at TTC!