when we first put Bay in a big boy bed we had massive problems!! i think he was about 19 months and his bedroom didnt even have a door! lol so we put up a child barrierand weathered the storm! lol he is also a super stubborn toad! so we had a week of solid screaming until 1am while we stated firmly every hour "its bedtime Bailey, goodnight" and after a week (may have been 2!?) the crying eased and he would jump back into bed after an hour until he eventually realised it was a lost cause to kick up a stink! - It was the hardest thing ever and we were sooooooooo tired!
Not looking forward to doing it with Astin because i sense that he will be utter trouble! lo
Good luck with it Kellz! youl get there in the end!