It is sunnah to break our fast as soon as possible when we hear the adzan. Our beloved Nabi Muhammad (saw) reported to have said that : The people will remain on the right path as long as they hasten the breaking of the fast.
There are a number of reasons why we should hasten to break the fast, one of them is to be different from the Jews as the Jews delayed in breaking their fast.
Ya Allah we beg You to grant us thoufeeq to follow the sunnah of Your beloved Nabi (saw). Ameeen ameeen ameeen Ya Allah