My daughter adjusted pretty well the 2 times she has been at 13 months and 23 months old.
She slept most of the outbound journey on both occassions and went to bed pretty much at her normal time so woke up pretty much at her normal time as well. We don't usually allow her to have a daytime sleep as when she does (even 15 minutes) she is wide awake long after her bedtime, so having a decent sleep on the plane helped adjust her body clock to the time difference.
Bookmarks