Just a quick reply, as I need to get to bed.
We "top and tail" the babies in the mornings with first cares. Weights are done by the night staff, usually right before midnight, and only once a week unless required more often. We weigh the intensive care/high dependency babies on a Sunday night and the special care babies on a Wednesday and Saturday night. For baths, they need to have been in a normal cot and maintaining their temperature there for a bit; and they tend to be getting close to 2kg by that point.