Did 10 mins later make a difference then? Are you capping the nap at their usual wake up time so that it is slightly shorter, and does that make BT a bit easier do you think?
We've just got through all the call backs, after a serious chat with DS but also I feel it is because he is getting through the developmental SA thing, his birthday is in just a few days so I think we've come the the natural end of the phase anyway.