I remember reading heatmiser's signature one day and it stated:
"You can wait forever, but no matter when you buy one, a new one will never be more than six months away."
I've been torn between which notebooks to get. But after reading that quote it just makes so much sense. There's no need to worry about an update. Look, Apple update their iPhone capacity yesterday but I'm not worried about it at all since I know I can manage with the space that I have.
I don't think it should matter when you buy one. Just be content with what you have. I think it'll save time and money in the long run.