I have just a couple of little questions and I hope I can find someone to help me out

Firstly, how can I say, I haven't been to Japan in 12 years? Would I use the 行った事がない structure?? If so, I'm not sure about how! 12年間日本に行った事がない would be my attempt. I'm just not confident with it!
Instead of that I could say, 日本に行ったから、12年過ぎました、OR 12年前に日本に住んでいました、or something like that, but I'm really wanting to know how I can say, haven't been.
Secondly, along the same lines, how can I say times flies? Can I say, 時間は早いものですね。??Does that make sense? Or is there a set phrase?
Thanks for reading!
お願いします。