Hi Charles ,
Well I planted out my chinese cabbage in august and covered in fleece. I then left it, with an occasional exasparated peek underneath, as it was completely obliterated by slugs. Oh well I thought, all good fun! 
But then the plants started growing strongly and I had a peek recently and hang on , there may be a heart in there.
In fact I just harvested a heart of 1kg! and others approaching that…. Success! beginners luck perhaps….
So the question is they seem ready now, but I am off on holiday for 1 week. Shall I leave them or harvest now to go in the fridge or leave till I return?
many thanks
Dan