Aidyn is 25 months and is still in his cot... I will probably keep him in there until the end of the year... so will look at moving him at around 2.5 years of age.
I'm definately going to go with a safety rail... he has had 2 falls from sleeping in our big bed in the past couple of months (), so I wont even contemplate moving him into his own bed without safety rails.

Lucy - I dont think 3 is too old to have them in the cot... I remember my Mum distinctl;y telling me not to rush Aidyn into a big bed, as I will soon realise how much easier it was to have him in the cot. I also am not looking forward to him wandering all over the place during nap time etc!
I might delay his move to a big bed until later, but it depends how much more he grows as he is already very tall.