Maybe if you prove to your dad that you're responsible before the end of the year he'll let you have it? Try asking him if you can get it early if you're really well behaved and see what he says. I really wanted a dog when I was younger as well - and I still don't have one! I found one that I fell in love with on my holiday but he didn't have a doggy passport and I couldn't afford to bring him home.
Try to understand that although you really, really want the dog sometimes it isn't fair on the animal that you own it. What I mean is that it's not fair for the animal to be stuck in the house all day if there is nobody around for him to play with. What if he needs the toilet and there's nobody in to let him out? Or what if you can't really afford to feed it properly - or you can't walk it by yourself cause he's too strong?
I don't think you're dad is trying to hurt you by denying you the dog, I think he is looking out for the best interests of the animal and your family. Hang on in there, play nice and I'm sure he'll give in eventually. Remember to be good to your parents because at the end of the day they won't be around forever.