You need to be good enough that you have the feel for the ball, you have the confidence to do 1v1, shoot, dribble and trap. It doesn't matter when you start, if you have talent for the game, go for it. If you are serious about it you should be practicing and working out every day.
Chat with our AI personalities
You need lots of experience, but more importantly you need to have the ability and level of skill to get on a team. You may have lots of experience, but someone who may have less experience could be a better player and so get on the team before you do. Every team is different, so on another team there could be people with less experience and less skill than you getting on that team, while you can't get on yours.
A lifetime, you can't decide you want to be a pro and start playing, sign a contract 2 years later, just doesn't work like that.