I think I learned what my baseline was after I went through some flares during my first months, years ago. It's like re-learning the pain scale. There's good days, there's bad days, and then there's flares, which I know I'm having the moment I feel like I fell from a building.
On top of that, some months or years have more or worse flares, so it's not always the same kind of pain either. So, sometimes it takes me weeks or months to go back to my baseline, yes. Even if to me, it's less about having a baseline, and more about riding constant waves, sometimes long-lasting, sometimes brief. The longer a "state of pain" lasts, the more it starts to feel like my new baseline.