Canna "COCO PROFESSIONAL PLUS+" Is that what is being discussed? If so, it does not seem to be available (or sold at all?) in the U.S.
I generally now use Canna COCO Natural Plant Medium" (their US bagged coco) or Royal Gold brand. With these and presumably other well-buffered, good quality control cocos, you shouldn't bother to rinse or flush up-front. But I always do a 15-20% drain-to-waste when charging the coco (with no prior rinsing/flushing), generally with about 25% feed strength. I'd be more concerned about rinsing/flushing any other additives, such as perlite and clay balls/Hydroton. If not a familiar, trusted brand/manufacturer, or if there is dust or other problem, consider giving these a good flush before mixing into the coco.