Stepping into Step 3

I'm beginning to plan my study schedule for Step 3 and had some basic questions.
1. How early in advance should you sign up for Step 3?
2. I plan to use MTB and UWorld, but what other resources would you recommend? Has anyone tried Amboss?
3. How similar did Uworld feel to the real deal?

If anyone starting to study for Step 3 would be interested in making a study plan together, let's do it!