You can't predict something like that. If you could, the world would be full of millionaires and no-one would ever go out of business...
What you need is an 18 month war-kitty. Work out your business plan based on not earning any money at all for 18 months. Make sure that you could survive this period of time, either through an investor's input or a supplementary income (day job). Budget for marketing, wrapping your vehicle, posters, and cards for chip shops, gyms etc. If you're able to do that then you stand a decent chance. Operating a successful paintball field is not easy, or necessarily fun. Expect to be sitting in your car every sat/sun morning wondering if people are going to show up. There will be tough times.
Nobody ever thinks about the tough stuff. Its too easy to think about money-fights, blow and hookers.
...as a quick pointer. The weekend will be your meat & potatoes. midweek bookings are the gravy, and hard to come by. You need to be able to operate 40 people twice per week in order to be able to grow and prosper as a field. As soon as you hit the 40 you need to re-invest and double your inventory so you can push for 80-100 per day at the weekend. Once you get up to 150 players per day you'll be making decent money. If you don't think you can get to these numbers that's a red flag.