Question about menses

Unfortunately I started my period on 6/21. I was really hopeful b/c she was to be here on the 18th. On Sunday, there was spotting and by 6am Monday, af was full force. But anyway, do you start counting your cycle when you first see spotting or is it by the first full flow? And also, Tuesday I passed 2 clots or mucus the size of 2 half dollars combined. Never passed one that big during menses. Does the size mean anything or should sound any alarms?