I got an email today from a man in Indiana asking when he should prune back his out-of-control Lonicera (Honeysuckle vine)and Trumpet vines. He knew that both plants are most often pruned during dormancy, and he didn't want to prune too late and kill the plant.
Well, the great thing about both of these vines is that they're remarkably hard to kill once they get going strong. The best time to prune both is during dormancy, since they grow their flower buds in the spring. If it's very early after dormancy, you might be able to prune them and still get flowers this year, but I don't recommend it. However, if you miss pruning them at the best time but still want to cut them back for summer, I would say that cutting them back after they are done blooming should be fine, so long as they are established vines (about two years old should be plenty).