"The pounding long-distance hikers put on their feet in a few months is similar to the wear and tear most people put on their feet over many years. As you age, the connective tissue in your feet loosens and your feet tend to get wider and longer. Depending on your physiology, this can happen in a relatively short period of time on the trail. Your weight and foot length can also be indicators of what to expect. Heavier people and longer footed people can expect greater change."
You can read more about this on my web site at http://friends.backcountry.net/m_factor/footchange.html .
Needless to say, I recommend not buying extra shoes in advance. And, if you're going in trail shoes or sneakers, you don't need to break them in in advance. They'll break in fast enough on the trail.
Also, I wouldn't go to a heavy boot to avoid buying more footwear. A pound on your feet is like six on your back. That's wear and tear on your body, legs, and feet. It can also slow you down quite a bit, too. Going from five pound boots to three pound boots and I sped up half a mile an hour without realizing it. There's a link to my hiking boots vs trail shoes page from the above page as well.
Hope this helps,
Mara
Stitches, AT99
Visit my Travels and Trails site: http://friends.backcountry.net/m_factor
NEW BALANCE run wide, is your foot wide?
Agreed. Plus unless you've already done lots of training miles and you've seen your feet grow and stop growing, then buying shoes early may end up being a waste of money.
Agreed again. Wear whatever is comfortable for you. Lightweight shoes are not comfortable for everyone. Boots are not comfortable for everyone. The best way is to find the best fitting footwear in the store that you can find, and then do a lot of training miles on them.