There are 40 days post partum that you'll be bleeding in any color, pink, red, brown. Don't worry about it, but you should not involve yourself in any intercourse until after you have completed the 40 days. It's unhealthy... Try waiting. It takes your body 40 days to get back to normal. It just had a baby coming out of there and the elasticity is trying to come back in place.
Hello sweet heart ! CD1 which in the frist day of full flow so no that is not the first day the first day is were you have full flow or reg flow ! Good luck ! Hope this help a little !