I took between 3-4 weeks off for CK which seemed par for the course among classmates. I did very well on my school OSCE so I pretty much just reviewed ortho exam stuff the night before and read through first aid for CS the day before CS. I know of someone who didn’t study and aced CS and I know someone who studied for about a week and had to retake. The timing of both tests is really dependent on you and your practice scores/comfort level. The relative timing of them to each other doesn’t really matter unless you are taking them in the same week or something. In that case I would take CS after, especially if you have to travel because it’s exhausting.