The expression "go the wagon" can be replaced with a few different synonyms, depending on the context and tone desired. One option is to use the phrase "hop on board," which is often used figuratively to invite someone to join in on an endeavor or movement. Alternatively, you could use the phrase "jump in," which has a similar connotation of getting involved or participating. Another option is to use the term "get on track," which suggests a focus on progress or forward motion. Finally, you could use the phrase "get moving," which is more direct and implies a sense of urgency or action. Overall, these synonyms offer a range of choices for effectively conveying the idea of joining or participating in something.