Hello! Took CS this past summer so here's my story:
So basically a quick run down on what the CS is. It essentially is a 12 station OSCE that takes about 6 hours or more and is offered nearly everyday in 5 cities in America. Philly, LA, Houston, Atlanta and Chicago. It is simply a Pass or Fail exam.
Each station is 25 minutes long. 15 minutes are spent with the patient, 10 minutes are spent afterwards outside the room writing the patient note on a pre-made template on the computer.
You are judged in 3 categories and need to pass in each.
SEP which is Spoken English Proficiency, the easiest portion basically assesses how fluently you speak English in the OSCE stations.
CIS and this is taken from the website (basically how well you can communicate with the patient in an organized way and how "doctorish" you sound: The CIS subcomponent includes assessment of the patient-centered communication skills of fostering the relationship, gathering information, providing information, helping the patient make decisions about next steps and supporting emotions.
ICE, the Integrated Clinical Encounter, which assesses your history taking effectiveness, the differential diagnoses you chose and why you chose them, the tests you decided to order, your physical exam skills and choosing the right exam to do.
Since it is a practical exam, the score report can take up to 2-3 months. The CS website has the score reporting dates for the next year already available and that is the most important thing to look at. To have a complete residency application, you need to take the exam before mid-July so your score comes out in time for when the residency application opens and you can submit your app However, even if you take it a little bit after (around August you aren't at a big disadvantage).
The tricky part is that since its offered in such few locations and nearly everyone applying for residency is taking it, it is often hard to get a date between April and July--so for the new graduates, I'd suggest scheduling it sometime between this Fall and January-February. The next thing you look at is whether you need preparation from Kaplan or if you can do this with a group of like-minded students.
The Kaplan course costs about 3500 dollars plus another 5-600 dollars for the hotel stay during that period so budgeting about 4,250 dollars would be needed. If you decide to take the course, you have to also make the decision quick because the seats fill up a couple months before the course (but be sure to ask for a waiting list in case someone drops out). The course is now done with 4 days of live online lectures that you can watch from your home or anywhere followed by 3-4 days at the Kaplan centers in New Jersey, Houston and Chicago--I believe. (Check out the Kaplan website for the details!) The last day of the course is a full length practice exam with actual patient actors and full feedback. If you take the course, I suggest take the course at least 1 month before your exam so you can get an idea of your weaknesses and have enough time to study. It's important to be friendly with the students at the course because often times when the course is over, these are the people you study with on Skype/Facetime etc. I found a partner who I studied almost daily with online for about an hr or two going over cases and planning the details of our strategies etc.--I did this for about one month before my exam date.
There are many people who study in groups and are able to satisfactorily take this exam without taking any courses and by utilizing forums/books/videos/and taking advice from others who have taken the exam. Most US students don't take any courses. If you feel confident, I suggest you speak to some people who've taken it, watch videos and find 2-3 other students who will study with you and go for it. Ideally, 2 months of casual studying will be enough--this is just a couple hours or less per day. (Just FYI, I took the Kaplan course so I can't help with a study plan for the above)
There is one other option--studying by yourself or in a group and taking the Kaplan practice test only which is offered at the Kaplan centers many times a year (again check out the Kaplan site for details). This full-length practice test comes with feedback and analysis and costs about 1000 to 1500 dollars and is quite useful in taking the mystery out of the exam so you are comfortable with everything the day of your actual CS!
SO that is what it is! Let me know if you have any questions!