Alright so i dont want to have until im married but..?

but like what happens if your first time you have hith him and you have like no experience or like you find out that hes really bad at it and them your stuck with him and having bad for the rest of your life! so should i wait until im married i want to but like i dont wnat to find out after i marry him that hes bad or do it with out experience already married for my first time..