I'm taking mine Dec. 22nd. I've had many programs ask about my step 2ck scores (even though my step 1 was great). They just don't want to match with someone who ends up failing step 2. Just make sure the scores are back by Feb.21st or whenever they turn in their rank list.
step 2 CS is specifically noted on the AMA freida site for each program as to whether it is required before starting a first year program or not...it's generally always required. CS takes about 3 months to get the results so you'd better take it early. CK takes about 4-6 weeks so you can take it later.
I haven't had anyone ask about step 2 scores during interviews yet (I've done 4 pmr and 2 transitional so far). I intend to take cs and ck in the spring. I have known students before me who have taken step 2 in April and matched at their top choice. That being said, this is just anecdotal and not statistical in any sense. Just thought I'd bring up that not having step 2 doesn't mean that you won't match where you'd like to.
It's really a difference between students going to US schools and those going to non-US schools.
All IMGs MUST have taken and passed step 1, CS, and CK before rank-order list time (Feb. 21st). No exceptions...well, unless you as prematching
US medical students can take step 2's whenever they like. If step 1 is good enough for you, don't risk getting a poor step 2 score...wait til after the match (or rank list submission).