Hello, I'm quite new to all of this, but from my experience coming off the pill (few years ago now) I just watched and waited for that fertile type CM as an indication that things were "going" again. I s'pose it can't hurt to chart from the first day of bleeding like a normal cycle, it will either be a normal cycle (good to chart) or not - good to chart anyway since it will give you more information if not immediately then maybe with the benefit of hindsight.
I was amazed when I re-read my journals of my first TTC journey - there are signs that my body was giving me that are so obvious to me now but I didn't recognise/understand them at the time because I was so emotionally wrapped up in it. Am going to try to be more Zen about it this time round...
Good luck with your TTC journey!