I'm not a sniper, don't own a sniper rifle, and probably never will. However, here's my take on it. Take my advice as you will.
Your previous experience will be of some value, but somewhat like having a private pilot license with small single engine civvie planes would be of value to flying a fighter jet. While that base experience is still there, there's a lot missing that you won't be able to get without working your way up from a basic rifleman -> designated marksman -> sniper roles. Until you have some solid, hands-on experience with those 'lower' roles in airsoft, I really wouldn't recommend jumping into the sniper role off the bat.
And remember - at most fields, if 1 person on the field objects to having a unknown / noob sniper in the game, that's all it takes and you won't be allowed to field your sniper rifle, even if you have BA certification. Being an airsoft sniper required more than just the base skills you already have, and for the most part, you'll need some serious airsoft experience before other players will have confidence in you to allow you to play the sniper role.
Personally, (nothing personal here), if you showed up at a game with a hot sniper rifle and your current 'qualifications' are all you had, I'd be the first to object to you field your sniper rifle.