At the beginning of the 18th century, dinner (the main meal) was taken around 3pm; gradually throughout the century, the time dinner was taken by the fashionable moved to a later time.
By the end of the 18th century eating a hot supper was rather old fashioned (as you had eaten a hot meal only a few hours ago). A cold collation of meats etc., was a more fashionable version of supper. Mrs. Phillips, in chapter 15 of Pride and Prejudice, is betraying both her provinciality and her old fashioned notions of style when she invites Mr. Collins thus:
“Mrs. Philips protested that they would have a nice comfortable noisy game of lottery tickets, and a little bit of hot supper afterwards.”
Recommended for further reading on this subject is both Maggie Lane’s book, Jane Austen and Food and Gully Lehmann’s most excellent work, The British Housewife: Cookery Books, Cooking and Society in 18th Century Britain.