The approved course list is from the Oracle site
here
The process is pretty simple, 1) register for the course, 2) attend course, 3) get course (attendance) certificate if instructor-led, 4) submit form to Oracle stating what course, when/where etc
The training can be done anytime before part 1, between 1 and 2/3 or after 2/3. The catch is Oracle won't say you have completed the cert until training is done.
Besides the instructor-led option, there are video on demand (VOD) and live virtual class (LVC). From my understanding, VOD is you watch bunch of videos that were recorded. The VLC is you actually attend class online real-time at a specific date/time.
Which course to do is up to you depending on your budget, time and schedule.