Newsflash: For someone to accept or decline a counter offer, do they have two days or two business days

Put in a counter offer on Thursday (Thanksgiving) & have yet to respond (Saturday). What is the latest they could respond? Would today be the last day or Sunday?

Read more at https://www.reddit.com/r/RealEstate/comments/e4138o/for_someone_to_accept_or_decline_a_counter_offer/?utm_source=ifttt