It's definitely too early to buy books now. Profs change, so just because a textbook was used last year doesn't mean it will be used this year. New editions come out (although you'll probably be fine with an older edition, it's best to double-check with the prof), so you can't just go with what upper-years tell you. Sometimes books are listed as required when they aren't actually.
There will likely be upper years selling books, and the Titles website has a classified section that you can use. I've sold books through there in the past.
Your friends are scrambling to get the best deals, but realistically they probably aren't. Usually, if you buy books from someone, they'll look at what Titles is selling the used book for and knock off a certain amount from that. Titles hasn't released most of the book lists yet, so you can't check what their prices are. Amazon and ebay can be great, but the books can also be a lot more expensive on there too, so you should at least wait for Titles' booklists to come out so you can compare.
There's no rush to buy books now, you have plenty of time!