How do I know when it is time to upgrade?

When you can name a specific friction that happens every session and a purchase would directly address it. If you cannot name the problem, wait.

Is it worth buying a monitor before a proper chair?

Usually not. A monitor upgrade while sitting in a bad chair just moves the problem. Fix the posture situation first, then fix the screen.

After your seated posture is comfortable and you want to vary your position throughout the day. Not as a replacement for fixing a bad seat.

Guide preview

Learn the right order to upgrade a desk setup. When to add a monitor, when to fix the chair, and what to keep skipping until the basics are solid.