Is it too late for progesterone?

Da

My husband and I are ttc number 4. I have progesterone to start taking on peak+3. I had my peak on Tuesday, CD 16. I was going to start progesterone tonight, but just had some pink spotting on the toilet paper. Is it too late to start the progesterone now, if I'm already spotting? My last few cycles have only been 24-25 days, and I've spotted for 4-5 days at the end of each cycle before my next period starts.