If we knew what it was we were doing, it would not be called research, would it?
– Albert Einstein
How do you know for sure that you are at a particularly interesting stage of your thesis project?
When the excitement spread to your supervisor, fellow students and the extended team (collaborators and others). When you present at a meeting and peoples come talk to you with that look in their eyes. When you are asked by scientists or other students unrelated to your project if you have published/submitted your results.
The flip side of that coin is that the pressure is on you (and your supervisor) to convert in a timely fashion to peer-reviewed publications 😉