Growing green peppers in a pot

I have planted some green bell peppers in a pot in the garden which have now started to produce fruits. I have not cut back leaves or anything just left to grow naturally.

When should I actually pick the veg to bring in doors to eat...i want them to grow as big as possible but don't want to leave them on too long so they begin to rot and die off.....

Is there a way to tell when they are ready to be picked and when they would be best for cooking etc? Unfortunately I do not have a green house or any indoor storage to bring them in over the winter...

Any advice greatly received. Thank you