Hi Sugarbevs.

I would personally wait until they turn red but if they are large enough when still green, they will have virtually the same heat as when fully mature so you could start using them.

Hi Fractal,

Many thanks. Some do look ready for picking ! Can I store them in any way; say by freezing?

For storing, when they turn red, you can dry them very easily which is the best way to store them. Put them in the sun or a very low oven for a few hours/days and they soon dry out. Then they can be kept in an air tight tin.
You can also mill them when dried to make your own cayenne pepper.
You can put the whole peppers in a bottle of olive oil to make a spicey oil.
For freezing, it's better to make a chilli sauce with other things like tomatoes and freeze the entire finished product.
Keep some seeds from the dried pepper to sow for next year as they will come true from seed.

Hi there Bertiefox.. thank you.