M was in a crib from birth until about 5 month old when we put him in his cot (cotbed) in his own room, he slept amazing, then at about 9-10 month old we took the sides off the cot and made it into a bed, another decision i dont regret.
M isnt walking properly yet so i was a bit weary of it, but he is so much better in a 'big boy bed', we dont even have a bed guard on because it was more dangerous him leaning on it, all i do is put a blanket on the floor at the side of his bed for when he does fall out (there is no if about it) i would highly recommend a cot bed rahter than just a cot, i think its just a logical idea really 2 in 1 and will last them for some good few years!