Does not look like UK has anything about 2018 Merit Weekend. But looking back at the thread for 2017 Merit Weekend
http://talk.collegeconfidential.com/university-kentucky/1961752-merit-weekend-2017-p1.html
it looks like some kids who had not yet received a formal Merit Weekend invitation were able to check their online account and switch to a Merit Weekend orientation (rather than a summer one). Also looks like people were getting invites in the US mail the first week or two in February.