Going in with this attitude is not good at all. I'd say don't become obsessed with DRY, because in the beginning it often won't be clear when it's appropriate to "fork" portions of the code versus adding a branch or two to the core logic. But if you go in with the idea that copy/pasta is the way to write code then you'll have important logic spread across dozens of places and it will become a nightmare to make what should be a simple change.