When you are "on course," it means you are heading in the right direction to reach your goal. However, there are plenty of other words and phrases that can convey the same message. For example, "on track" or "following the correct path" can be used to indicate that progress is being made towards the intended outcome. "On target" is another great alternative that suggests the goal is in sight and can be achieved with continued effort. You might also use "making headway," "moving forward," or "progressing as planned" to describe a situation where things are on track and proceeding smoothly. Ultimately, the words you choose should depend on the context and tone of the conversation, but hopefully this list gives you some ideas to work with.