You need to have been enrolled for one ACADEMIC YEAR (not necessarily 9 months) to be eligible for OPT prior to completing your studies.
You need to actually COMPLETE a program of studies, rather than just abandoning it to qualify for post-completion OPT. You're well advised to make the post-completion application BEFORE you graduate from your program of studies. You can technically apply during the 60 day post class time, but you're risking it.
You can't just give up going to school and go to work and call it OPT.
Your school DSO should be able to advise you.

