In the Netherlands/Belgium it is possible for people who never touched a weight to train for 3 months. Then they are competitive enough for the C-division. Think about Atlas Stones 70kg up to 125kg. Log Press starting with 70kg, Yoke around the 200-250kg. Medley with a 250kg tire, 125kg Duck Walk, Farmers with 75kg. Power stairs with 125-150-175-200kg for 4 steps, Load race with 75kg Kegs. Load Race Keg on pallets 110kg on 1.10metres All doable within 3 months if you've never touched a weight in your life.
End of their first season, or the start of the second season, those same people can compete in the B-division. Farmer Walk around 100kg, Yoke 300ish kilo's, Tire 300-350kg, Truck Pulls, Stones that go up to 150-160kg, Log starting at 70kg and ending as high as you can, Fat DB Presses for reps at 45kg, Power Stairs going tot 225-250kg, Keg Loading on pallets 135kg on 1.2metres, Front Hold with a car battery...etc.
After they are strong enough to end top 3 in several B competitions it is time to move into the A-division. When you're strong enough to stay in the upper regions it is possible to compete in several qualifier competitions. When qualified you will compete for the title strongest man of the country. In these "divisions" you have to work with the heaviest weights possible. Tires of 380-420kg, Yoke with 350-400kg, Stones up to 180-220kg depending on which heights are being used, Power Stairs up to 325-350kg.
When you finish top 2 you'll be invited for the Champions Leageau and compete against the strongest men of Europe. Finish up high in that competition and you'll get invitations for Met-RX world strongest man, Fortisimus etc
Usually it is viable to take 2 years of time before you go up to the next level so the speak. Some are more talented then other individuals and go faster or slower to the top.
Over here we don't waste time on weight classes and age differences. If you're strong you're strong...if not...you're not. Still there are several organisers that create competitions with weight classes. It is a shame if you ask me. You need to look at the list of events and ask yourself if you can compete with that. If not you should stay home and try another competition.
Experience is important. Still I wouldn't compete in as many competitions as you can. Your body needs to adjust to the stress. During the first year you'll also have to adjust your training schedule taking in account possible periods of rest and what not. Try to have 1 competition every other month for the first season as maximum. Increase amount of competitions the year after when your body has acclimated itself. You have Gym experience, but I'd get some event training experience first. Get some basic experience with the events themselves before entering a competition.