should i get a new pair of running shoes

I would definitely get a new pair. I think you still have enough time to break them in before race day. To run 26.2 miles on a pair of shoes that is that old, or has that many miles is not the smartest thing in my opinion. I think your body will thank you both during and after the race if you purchase a new pair for race day. If you are worried about blisters/fit then put some bodyglide or vaseline on your toes and heels and that should minimize any blisters.

thanks for your response, but i meant get a new pair of shoes to train in.

I have a pair of road racing shoes already.

Also, I'm only doing a half marathon.

I don't think it is going to make that much of a difference if you aren't going to be racing in the Nimbuses.

The only reason you would normally give yourself a couple of weeks on a new pair of shoes before the marathon is if you plan to race in them. If they're just training shoes, I highly doubt it will make a difference, as long as you don't start developing blisters or injuries.