How do you get Stellarys?

Celestice is the route, which means the work you do to get Stellarys is work you were going to do anyway. Push the progression forward and it comes to you. There is no separate hunt to plan for and nothing to save up before you start.

Early is the other half of it. Stellarys lands in the early game, not as a reward held back behind hours of later content, so a new account reaches it on the normal path without detours. If you are playing in order, you are already heading towards it.

Not settled: Celestice covers a stretch of early progression, and the exact point inside it where Stellarys arrives is not pinned down.