We are still waiting for a few days of sunshine and the ripening of the many green tomatoes that are still on the plants.
If your first toms are still green but full size, I recommend that you feed (with tomato food of course) twice each week or every other watering. This should bring them on and hopefully get them turning colour.
However, don't exceed the manufacturer's recommended feeding instructions for more than three weeks or you may damage the plants roots due to a build-up of nutrients in the soil.
Also, if you are concerned that you have given too much or the strength of the solution was more than you had intended, give the soil a good flush through with clean water.
I still have some varieties such as Alicante without one red tomato, yet Red Alert has been fruiting since June!
If you wish, as soon as a tomato begins to turn colour, pick it and put it in a bowl with a ripe banana. The ethylene (?) from the banana helps ripen toms more quickly.
Thankfully many of the varieties I grow are producing ripe tomatoes and one of the stars of the season has been Maskotka, a cherry bush variety. The fruit are large for a cherry tom and the quantity and taste are also very good.