We went skiing when DD2 was 2.5 so I tried training her around 2 like you're planning to do - she had no clue! I persisted for a week then decided that it wasn't worth the stress and gave up till afterwards. In some ways, it's actually easier to travel when they're in nappies - none of the "I need to do a weeeeeee!!!!" when you have no idea where the loos are or you're on final descent in the plane So yep, give it a go, but don't be too worried if it doesn't work out