Ovulation right after last day of period:

Is it possible to ovulate as soon as your period ends? We've been trying to get pregnant for several months now. I'm still in the process of charting my cycle now that I'm off bc & returning my body to its natural cycle. I've been using Clear Blue Advanced to aid in my fertility quest having no luck so far. Frustrated, I decided to test my fertility almost everyday. A day after my period slowed to spotting I started testing again, I got a peak readying (probably a false positive), but I've now had two high fertility readings. My bbt & other indicators are not clear. So, I'm now four days removed from my last period day & getting high fertility readings. Is it possible to be ovulating so soon?