Hello and thank you for always being so helpful!

I stopped taking my active pill on Thursday night. On Shabbat I noticed a small spot on my colored underwear and told my husband that we should wait for a flow a bit longer. A few hours later I asked him to bring me a tampon (which indicates a flow and in my mind is the onset of nidda status). From that moment we began all harchakot. In my mind we were in nidda. The next day on Sunday, he asked what our status was. We were at my parents' place and busy with kids and there was a miscommunication.

My question is when we begin counting our five days before hefsek tehara. I would hope from Shabbat when I thought it was clear that we were in nidda but as my husband was not sure still on Sunday I thought I would ask.