Are they indoors or out? Are you norf or sarf? Here in Cornwall I have to grow them in a greenhouse. I only grow cherry toms these days (always Sungold). By about late October the plants are getting knackered and ready for pulling but I shall still be getting a few red toms by then. Toms ripened indoors never taste much good raw but they cook up well and make good chutney. Leave 'em on the plants for as long as you can I reckon.