The location fore and aft where the mast is stepped is controlled by the Class rules.

With the mast spar perpendicular to the base line, the after side at deck level shall not be less than 3048mm and not more than 3202mm forward of Station 11 (the transom)“.

Some people step their masts as far aft or close to as far aft as possible. HOWEVER. You generally do not want the aft end of the mast to touch the back of the deck level gate when you rake. If it does so too early in the rake range,