I personally do not see a need to inform NVC of address change since your P3 has gone to the consulate. But since you have already informed other authorities youmay want to call NVC and ask if they require an address change form to be submitted. Address change ideally does not affect / result into a postponement of CP interview.
If you request initial CP interview postponement, your 2nd cp interview is generally scheduled more than 60 days after but less than 365 days after the originally scheduled interview. IOW..greater than 2 months, less than 12 months. Someone from my company requested postponement last year and he got second interview in about 3.5 months after originally scheduled interview.
Disclaimer: I am not a lawyer. My replies are based on knowledge gained on immigration sites & my studies on US immigration. It is always good to consult an immigration attorney such as Rajiv Khanna. If you have specific questions for me, please PM me.