How to detect CD1?

So I started spotting yesterday (Friday)... I’d say for the first half of today (Saturday) it was spotting but then I had a spout of bright red and much much more so I thought it was my full blown period... next time I went to the bathroom it was still there but very very light... then back to a lot more.... then back to very very light. Every single time I’ve wiped today there is SOMETHING, but not full blown red flow. Is today my first day of my period, or is that still spotting? I’ve had my period for 15 years and this spotting is new to me and very confused of what day 1 actually is. Also, I’ve had pretty uncomfortable steady cramps since yesterday.