Why did you invite him over for dinner? That's a great idea to have D make him a cake, maybe even help her pick out a present for him. But you shouldn't invite him over for dinner, that smacks of pursuit and desperation. It also lets him know you are firmly on the hook as Plan B which is not where you want to be! But if the plans are already made then yes, no R talks. Dress nice, show him what he is missing. Be positive and upbeat and talk about nothing you wouldn't talk to a casual neighbor about.
As for the random text, on stuff like that the rule is sometimes reply right away, sometimes an hour or two later, and sometimes not at all. The idea is you are too busy to reply to all his petty texts.
