Fiance Visa - K1/ K2/ K3/ K4

Hello to all, I just sent my fiancés K-1 paperwork to the Dallas office a few days ago. I know it takes a few weeks for them to send noticafication to me that they've received the paperwork. My question is that him and I plan to wed on December 11,2016. With that being 7 months away should we change the date? I am trying to figure out what the time will be from them approving the visa here, sending it to Addis Ababa, Ethiopia, him getting his interview, him getting his visa to travel here. We are praying that all this can be done by the end of November so we can buy the plane ticket a week after he gets the approval. So I would like to know the timeframe from start to finish with him getting here from Ethiopia without there being in delay on our part. I've made sure I sent everything that was requested and I have copies for him also. So we just have to do the physical examination, get the police report, and rollout his application for his interview. We've already set aside his interview fee that's $295.00. If anyone can give me a timeframe of getting the person here to America without the other process of getting the green card. I should get a notice by mid-May saying they've gotten the paperwork. I just need to know if we should change our wedding day for 2017. Please help, thank you very much.