When to move to a bed

[FeakAndWeeble]

DS is nearly 18mo and has been walking for a month or so. He has a cot that turns into a bed.

At what age am I supposed to actually turn it into a bed for him?

At the moment, he goes to bed very nicely at 7pm - he ususally asks to be put up by pointing upwards and saying 'N'night'. When he's up there though he plays in his cot for 40 minutes or so, singing to himself and moving his toys around, then lays down when he's ready and drifts off. I'm a bit worried that if I move him to a bed now, he'll get up and start running about upstairs rather than just playing in bed. He likes to have his bedroom door shut (he yells at us if we leave it 'to') and I'm not even sure if you can fix a gate across a closed door. But also, I don't want him in a cot longer than he's 'supposed' to be in one IYSWIM....

(Can you tell he's my first? )

Is there an age you're 'supposed' to do this?

When he starts trying to climb out of it.

So the only 'rule' is don't change it unless it becomes dangerous.

my DD1 was in a cot till 2.8 she never tried to climb out so i left it till i was sure she was ready.

If it ain't broke, don't fix it... He sounds perfectly happy as is, and as has already been said, as long as he's not trying to climb out of the cot leave him in it if he's happy.

We put the cot mattress on the floor at about 16 months and then he went into a full size single at about 19 - 20 months ish all a bit hazy now