I have (setq org-read-date-prefer-future 'time)
in my .emacs, so if I give a time like 8am and it is before now then it is interpreted as tomorrow. This is good, because I never want to set times in the past. However if I give "thu 8am" (it is Thursday 11:50am here, so Thu 8am is before now) then org interpretes it as 8am today. When org-read-date-prefer-future is set then org should also interpret times given as day+time as future times if the day of week is the same, but the given time is before now. That is, in this case Thu 8am should be interpreted as 8am next Thursday.