I wanted to reply last night, but my internet went down. It's probably going to lose connection again as soon as I try to send this. But thinking about it overnight there is probably nothing useful I can say because I live in a different country. As far as I know there isn't any kind of statute of limitations here. I've read cases where people have been prosecuted like 30 years or more later. I guess there is no better time to do it than now if you've going to be up against that later on.
2 of my 5 have been prosecuted and are currently in jail. Both times I was a minor though and basically had no choice in the prosecution process. Both times there was a lot of evidence - even though one had happened 5 years before (pictures on his hard drive). But I was told by the police originally (before the pictures had been discovered) that my statement would be classed as evidence - so you might not need anything physical. I don't know how your justice system works, but here the police send all the statements and evidence to the prosecutors, and they get to decide if the case is worth taking to trial. I had to go and meet with them for one of the cases to be interviewed. (The day before one of my exams at school). They need the case to have enough evidence and a realistic chance of prosecution and it has to be in the public interest to prosecute. But with rape and abuse cases it's always in the public interest to prosecute.
I didn't have my own lawyer, basically I became a witness and it was the prosecution service against him. I would think that unless it's you yourself bringing a case against him in a civil court you shouldn't need your own lawyer. But I'm in a different country, so I don't know that for sure. Once you give your statement to the police what happens next is pretty much out of your hands. I think you should speak to your therapist first. I imagine he/she would have training in stuff like child protection/disclosure, which I know doesn't apply but I'd think that would give them half a clue about the legal process and what you should do to start it off. You might want them as your support person. It's a long long process and I always felt like we were kept out of the loop. In a way it wasn't like my story any more, it was their case and I was just a minor part of it.
I don't really feel much of anything about them being in jail. Glad I guess that other people are safe from them. It seems like once the legal stuff was done then it would be over and I could move on but that never happened. And my uncle continues to harass me from jail anyway. But I think it's a good and worthwhile thing to do whatever the outcome is. He absolutely SHOULD be held accountable. Good luck.