The best time to repot any sympodial is when new growth has just started to appear. The growth will emerge first, before any new roots, and if you repot then, the new root system will develop into fresh medium. That'll compensate for the inevitable (however slight) damage to the old root system that occurs when you repot.
That said, we've repoted Catts anytime from early spring till early fall (active growing season), but never when the sheaths are showing buds. If your sheaths are still flat and empty, you can repot (and even divide) with no harm to the plant or flowers as long as you keep at least 4 growths per division and the old root system is healthy and strong.
Bear in mind that any aerial roots which have developped will more than likely die when submerged in bark mix, so if you have a lot of those, wait until new growth develops from an eye and repot then.
As far as the "repot immediately after blooming" adage goes, that all depends on when during the growing season the plant bloomed. If it bloomed in spring, by all means repot: you know that new growth and roots will develop before winter. On the other hand, if the plant bloomed in fall, I would wait till new growth appeared the following spring before repotting: the plant will winter over in much healthier shape if its roots aren't disturbed.