Normally, the fall editions are not officially announced until the May upfronts (which is usually the week of TAR's spring edition finale or within a week or so thereafter.
The application prior itself more or less means that there has been a grennlight, even though there may not have been an episode order placed; most networks often have their week-by-week preliminary schedules done it seems up to a year ahead. (That's helps them plan for development of pilots which often does start almost a year ahead.)
The fact that Nancy Tessler has already indicated that CSI:Miami will be renewed even with its higher costs, and lower ratings, and is seen as an improvement over the other dramas that have been in the 10pm Sunday slot over the last few seasons (Cold Case, Without A Trace, The Unit), is a preety good indicator I think for TAR 19 and 20; especially her line that if the fans keep watching then they wouldn't be canceled.
That's my $.02 anyhow.