I would buy them now. Boots are a lot better than they used to be - the old hard leather ones took a couple of months to break in, but I would wear them round the house.
If you are not used to buying hiking boots make sure you go to a shop where someone knowledgeable can help you get a pair that fit and suit you. They fit very differently to ordinary shoes or boots. If you get a pair that "feels right" in a shop without advice, unless you know how walking boots should feel I can almost guarantee that your toes will be cramped going down hill and there will be uncomfortable rubbing on the top of your foot after you have walked a few miles. Getting the right fit is much more important than breaking in.