We did the big bed first, only cos DS was rolling around like a mad man in his sleep waking himself hitting the cot rails

Also, re the TT, we day and night trained at the same time, worked a treat. One thing to consider is if you put the nappy back on at night you may confuse them, or if they are only comfortable to go in a nappy they may hold on ALL day until the nappy is on - just something to think about, you'd know best for your own LO though