I didn't follow my CP as closely as I followed other symptoms - but there was definitely a difference this last cycle when I got my BFP. Normally my cervix would firm up and be drier starting a few days before AF, but this cycle is stayed high and wet, one of my first clues. Hope that's helpful! I will say that I noticed a lot of variation in height throughout the day though, so if you're going to track it I would suggest picking a time of day and checking it at that time only, kind of like BBT.