Film production happens in phases, and the time it takes to push a movie through each phase can vary widely. While most films take from a few months to a few years to go from pre-production to release, a few have taken quite a bit longer.
One outlier is Orson Welles’s The Other Side of the Wind, which began principal photography in 1970 but didn’t see theatrical release until 2018 due to legal and financial problems. While many things can affect the timeline, if you understand the ins and outs of which type of movie you want to make, you can gain a better estimate of how long it will take to create.