With the entire tech world eagerly waiting for Apple’s expected announcement on September 10, the question on many consumers’ minds right now is when they should get rid of their old smartphone. Unbeknownst to them, waiting too long to get rid of their iPhone could mean losing out on a substantial amount of money. Instead, what we have found is that you should already be locking down a good rate for your old iPhone clunker as soon as possible – and definitely not wait until the new release. So how do we know this? Recent used iPhone sales and depreciation data suggests that instead of waiting to sell your old iPhone, you should actually be locking in a higher sell price BEFORE the new model launch – and then using the proceeds to help fund the cost of your new iPhone. Recently, we examined hundreds of used iPhone sales on our uSell.com website following the 2012 iPhone 5 launch. By aggregating this price depreciation data, we found a surprising result. Old phones lose a great deal of their value each week after the new iPhone launch – starting at just seven days after the new model announcement date. Interestingly, one week after a new iPhone launch, old iPhones lose about 5 percent of their value. By two weeks after launch, old iPhones depreciate about 12 percent. By weeks 3 and 4, old phones are worth about 20 percent less. That’s a huge depreciation in only a few weeks. So how much more can you get for your old phone if you sell or lock in your rate now?  We ran the numbers:

An iPhone 5 is potentially worth $72 more (compared to 3 weeks after launch)An iPhone 4S is worth $46 moreAn iPhone 4 is worth $29 more

So by locking in a sale price BEFORE an upcoming iPhone launch (many platforms like uSell.com, which I founded, offer 30-day price guarantees), you can substantially increase its value. So the key is not to wait. Even a few weeks will bring down the value of your phone substantially. And why sell it for less if you don’t have to? Guest author Nik Raman is chief operating officer of uSell.com, an online marketplace that helps you sell your used electronics in three minutes or less through a network of professional buyers who competitively bid on your gadgets. Nik is an expert on the used iPhone industry and helps create the user experience for uSell.com’s smartphone marketplace. Nik’s path in the “re-commerce” industry began as founder of EcoSquid in 2010, an electronics trade-in and recycling aggregator that uSell.com acquired in 2012. He is a graduate of Harvard Business School.