Do implatation symptoms happen if implantation is successful?

Iris

Ive been having mild cramping at 6 and 7dpo and today 8dpo ive had nothing. I never get cramps this early, earliest is the day before my period. I had a chemical last month and didnt have these sort of cramps either (they lasted about an hour or so) and come and went through out the day. Im curious if implantation symptoms indicate implantation was successful? Or is it just my body gearing up for implantation?