I want to take step 3 and there are certain things I want to know:

What is the optimal time it takes for an average candidate to prepare for step 3?

Also, what materials do you recommend?

How long does it take for local state boards to approve the applications?

Sorry if the questions sound stupid

i would say it takes around 3 months (4 hours/day).
CCS(Dr red) + lectures (Dr Red) + MTB and Uworld and NBME (go though differentials!!)
Dr red can be found at ccsworkshop.com
the reason i recommend him is because he gives us all the guidelines and that way you know when to do what. no other book/online q bank does this.