CK experience:
3 months of preparation; all uword notes hand in hand with offline uworld by system… then 1 time uworld online mix ( then I repeated the wrong questions)
Didnt do any extra resources but I studied kaplan internal, obs&gyn back in med school.
Didnt do any NBMEs
USA1:273
USA2:259
Exam: 253
I took my exam in 16/8/2019 it was the new pool of questions, the exam was horrible and full of stupid questions, and the questions were super long… so Iam really happy with this score…
If you need any advice dont hesitate to ask 
Good luck