we tried to stop him putting his knee through the cot bars for weeks, but nothing seemed to stop him. He'd do it as soon as we walked out, and he was getting it very stuck, took 2 hands to get his knee out. What would you suggest to deal with that
Very similar to what you are doing now. Your focus is on lying down in the cot. Don't tolerate anything other than lying down in cot.
Child stands up.
You lie child down, re-settle, establish calm lying down sleep time and walk towards the doorway
Child stands up.
You lie child down, re-settle, establish calm lying down sleep time and walk to the doorway
Child stands up.
You lie child down, re-settle, establish calm lying down sleep time and walk to the doorway, wait in the doorway.
Child sits up.
You lie child down, re-settle, establish calm lying down sleep time and walk to the doorway, wait in the doorway.
.... and so on until....
Child stays lying down for 15 minutes, you take a few steps away from doorway but leave door open. If child stands, repeat as above. If not wait until child is asleep and then close the door.
The behaviour issue here is that the child is not lying down and relaxing at bedtime. This issue is the same bed or cot. It is just much, much easier to deal with in a cot.
I know quite a few people that moved their kids to cots around 2, some earlier, so didn't seem too early. I hadn't planned to do it yet
This decision is not yours, that is the problem. If you remove the behaviour issue and moved from cot to bed at a time that you felt was right for your child, then the age doesn't matter. The move from cot to bed should be positive, a nice change that is easily done.
You have not made the decision to change from a cot to a bed though. You have allowed your childs behaviour to force a decision before it is actually the 'right time' in your adult view.