jack went into his big bed the night of his 2nd birthday. charli was due a couple of months after that so we wanted him to get used to the bed before she came. he moved into the bigger bedroom too which we painted up for him so we made it into a really special thing for him.
he slept in the bed the whole night and we've never had any problems at all
we'll probably look at putting charli in a big bed just after her 2nd birthday too. hopefully, she will cope the same as jack did!