Advice on pruning espalier crab apples

I'm looking for some advice. I have a line of espalier crab apple trees that I suspect have not been pruned for the last 3 years. They have become overgrown and there are now some large mature branches that have grown perpendicular to the horizontal espalier line (closeup of example in second picture growing over the hedge). I did some research and understood that this is the best time of year to prune trained fruit trees in order to restrict growth. Am I safe to prune back the trees now, including a fairly significant volume of large branches? I showed the pictures to a local fruit garden who suggested that this constitutes major restoration and should be left until winter. This contradicts what I had read and thought that I had understood and I'm now confused about what to do and when. Any advice on this would be welcome.