Melissa when Sophie was almost ready for the transition but not quite we had some truly awful nap days- the worst were one day at home with me when she had 2 x 10 min naps, and one day at nursery when she refused at nap AT ALL! But then the next day she would nap like an angel
I think this whole thing is really unsettling for them as they don't know what's going on with their routine, their body clock is changing amost daily, and you're bound to get some sucky days. I kind of stopped analysing how each day was going, and sort of shrugged it off when I had a bad day and tried to go with the flow a bit (really hard for me, I am a total control freak!)
Most of the time there seemed to be no discernable reason for a bad nap day that I could figure out, it's just one of lovely things about this transition. The only thing I could put my finger on was that if Sophie had perhaps spent a lot of time in the pushchair or the car, she didn't then nap well and I guess it was because she hadn't done enough physical activity so wasn't tired enough. Maybe that's what happened with Grace?
Come join in the 2-1 nap thread there, we all have loads of horror stories to share
and of course advice to give!