I met two different couples who literally sold everything, drove to Florida, bought a boat, had an instructor on board for a week, and sailed away with no previous experience. Neither has gone past the Caribbean but they both did fine. One of them now runs a day charter on a catamaran.

I spent several years learning and improving sailing skills before heading off. 2-3 years of weekends and a few vacation weeks would probably do it if you started with that as your focus. It takes a lot of people that long to find a boat and get it set up the way you want anyway.