To animate and film one episode of Family Guy it takes months to complete the animation, voice acting, script writing and filming of the show.
For one small episode of Family Guy it takes from 9 to 12 months before one Family Guy episode is complete.
Several people are working constantly to get the Film made and ready to show. More than one episode is being made during those 9 to 12 months so they'll have another episode of Family Guy ready.
It's estimated that it costs 1 million dollars to make one episode of Family Guy.