There are many synonyms for the phrase "starting line" that can be used in various contexts. One option is "starting point," which refers to the location or point in time where a journey or task begins. Another option is "kickoff," which typically refers to the beginning of a sports game. "Launch pad" is a phrase associated with space exploration and refers to the place where a rocket begins its journey into space. Other options include "jumping off point," "onset," "genesis," and "commencement." Each of these synonyms can add variety and interest to written or spoken language when used in place of the more traditional "starting line".