As Elizabeth tells Charlotte in ch.6, Jane "saw [Bingley] one morning at his own house, and has since dined in company with him four times" (since the Meryton Assembly), and I imagine Elizabeth has met Darcy on the same occasions, so I don't think Elizabeth can still be hinting about Darcy's behaviour at the MA when she mentions saving her breath to cool her porridge. Also, I'm not sure Elizabeth would hint that Darcy should keep his mouth shut, since one of her problems with him at the moment is that he *won't* talk - he just stares at her and silently listens in on her conversations with other people!