Should I buy nocturne... if I do.... how long will it take to get the 6k IP back?

if you like jungling

Do you consifer him OP late game or early game?

He's good if you know how to play him, but there is a learning curve... He can jungle and lane, his ult can fling himself to any enemy in a large range

?

Its your choice, all champions are good if you know how to play them. But don't buy him just because he costs 6300, because a 450ip champion is just as good. the 6300ip will take some time to regain back. Seeing your match history maybe you should read some guides on builds, and positioning.

I've played Nocturne a bit and he is really fun. I bought him when he was on sale a while back and I thought he was worth it.

I've played him bot and recently tried jungling with him. If you've played Garren, use a similar tactic. Hide in the bush and then ambush! I've watched a lot of amaizing ganks on youtube and I find it a useful tactic for when you use your ult to jump them, I prefer to when they are under a tower..all alone..and ult jump them and instantly use my fear teather, and use my q to just lay down the dmg wherever they decide to run to. Me and the tower double team him/her. Take that dunkmaster yi!

He's fun, but does indeed have a learning curve. Also he has a really stunning jungle clear <3