Well, let us see. Darcy is in a bad mood at the Meryton ball. Bingley comes up with the instruction to dance, Darcy insults Elizabeth's looks.

...when they next met, he looked at her only to criticise. But no sooner had he made it clear to himself and his friends that she had hardly a good feature in her face than he began to find it was rendered uncommonly intelligent by the beautiful expression of her dark eyes. (chpt 6)

So it sounds like at their first meeting after the ball (from your quote this was in the morning at at Netherfield House - my guess is that the Bennet ladies called on Caroline and Louisa) Darcy was looking only to criticise. He probably discussed his opinion of Elizabeth's looks with the Bingleys after the Bennets left. I can't see even Darcy being so rude as to make this clear while Elizabeth was actually there.