[CentOS] Text Proccessing script - advice?

Tue Dec 21 17:30:03 UTC 2010
Roland RoLaNd <r_o_l_a_n_d at hotmail.com>


I have a log file with the following input:
X , ID , Date, Time, Y

My goal is to get the number of times ID has a TIME that's after 09:00:00 each DATE.
That would give me two output. one is the number of days ID has been late, and secondly, the day and time this ID has been late .

I've started as such:

sort -t ','  -k 3,3 -k 4,4  file.log  # this will sort the file according to the DATE field as well as the Time fileld.
I'm stuck for the last 30 min to find a way to get the first line of each day (logically it'll be the earliest as i've sorted by date/time previously) once i know how to do this, i'll be able to compare time and proceed..

Can any one help ?
i looked into sort - u and uniq -f3 though i didnt get far with it..