I used an OPK for the first time this month and started testing on thursday and then had a +ve on the Sunday morning around 10.30am

I was also getting really strong cramping at tea time on Sunday Night. Would the cramping have indicated when I ovulated ie: would this be Day 0 and Monday Day 1po or would I have ovulated on the Monday making Tuesday 1dpo?

This is all so technical!!!!

I have been getting slightly sore BBs and a small amount of cramping Yesterday, but other than that everything feels normal. I never got sore BBs in my normal cycles previously.