I think putting a person's experience in terms of "years/months" gives a very incomplete picture - you'll understand how much work and effort was for getting to a certain level if you ALSO ask how many hours of on-ice time that person was doing a week for that time. People have various physical and mental aptitudes that allow them to progress at different rates, but the amount of time they spend on the ice is very big factor.
For me, I skated through my teens, but only skated 60-90 minutes (with a 15 minute group lesson in there), once a week, about 8 months a year. I got to my first (half-revolution) jumps fairly quickly (months?) when I started taking lessons at a skating club. (I had already learned the basics of forward and backward skating at the town rink lessons.) It probably took me about 4 or 5 years to get all my single revolution jumps (toe-loop, salchow, flip, loop and lutz) down, plus learning the basic spins - upright, sit and camel. I'm sure that I could have made much faster progress with more ice time and private lessons, but I was happy with having skating as a low-key activity.
I've read more than one account of kids who totally love to skate and practice many times a week and make rapid progress.