When to let kittens out alone?

[dementedpixie]

My 2 kittens have just reached 5 months old and I have been supervising them in the garden. One of then keeps climbing up the middle of the tree or the fence and I keep bringing them back down. At what point do you just leave them to go where they want? They are neutered and microchipped

Nobody had this issue before? Please advise

I did it at about 9 months. Partly due to time of year. Before that they were on leads.
Once they were off they were off and gone though. Spent several months worrying when they weren't back in the house before dark - but they always came back at some point. They're now five years old and keep pretty regular hours.

Have they had their injections?

We let ours out from 6 months. She kept to the garden for a while, but we figured she'd explore further when she was confident she could come home again.

Yes they've had injections, flea treatment, worm treatment, etc and were neutered recently and got their microchips. I'll maybe keep them enclosed for another few weeks before letting them go further. Keep having to pick one out the middle of a conifer tree though as he is so fast and just clambers up the trunk using the branches.