I just change mine on Thursday night when I go to bed and then Sunday night when I go to bed because I began to use it on a Thursday. I've always done it this way. It says on my packet Thurs/Sun, Fri/Mon, Sat/Tues, Sun/Weds, Mon/Thurs, Tues/Fri, Weds/Sat. You stick to the same routine all the time so depending on which day you began the patch this decides when the changing day is. There is no need to go into half days.
Thursday and Sunday is right.
Taz x