To participate in the National Resident Matching Program® (NRMP®) Main Residency Match®, international medical students/graduates must have passed all exams required for ECFMG Certification. If you plan to participate in the 2020 Match (in March 2020) and still need to pass Step 2 Clinical Skills (CS), you should register now to take the examination.
To help ensure that your result will be available in time to participate in the 2020 Match, you must take Step 2 CS by December 31, 2019. If you do not register now and schedule soon, it is possible that you will not be able to obtain a test date in 2019. At the time of this writing, the earliest available test date at any test center is in September 2019.
This is copied from ECFMG website
Here is the link