Tomatoes that grow beyond the truss

I'm sorry, there must be a technical term for this, but for tomatoes that continue growing at the end of the truss I'm wondering when or if you normally stop them, and if it is bad for the plant?
I have one growing up a string, variety as yet unknown because it comes from a mixed pack, that cannot be left to grow on this way because of lack of space. Is it best to cut off the growing tip as soon as it is obvious, or wait for the fruit to set? And how much do I leave - one leaf, nothing? With grape vines I always cut back to one leaf beyond the bunch of grapes, perhaps these kinds of tomatoes would do well treated the same way?!
I think I usually just remove everything beyond the fruit, and blight aside, tomatoes seem to be pretty robust!