If you're the type to sell one phone to help pay for another, you've got some research to do.

We know there's something big right around the corner from Samsung. In fact, there's a good bet we're actually going to see three somethings. Chances are more than a few of you are waiting to see if the Samsung Galaxy S7 is going to be your next phone, and a big part of that wait is deciding the best time to sell your current phone to help offset the cost. Choosing when and how to sell your phone is a big deal, especially when you consider you're not the only person having that idea.

To get a better idea of how well big brand phones have sold in the past as a new phone neared release, we sat down with folks from Swappa and eBay to get an idea of what to expect as we get closer to the announcement of Samsung's next phones.

Galaxy S6 Swappa

In order to better understand the way phones are sold on services like Swappa and eBay, you have to first accept that there's a whole lot of people out there who aren't rushing out on day one to purchase the latest and greatest from any one manufacturer. The secondhand market is filled with thrifty folks who know the price of a gently used Galaxy S6 is going to come down when the Galaxy S7 is released. Since that's still a great phone, there's no sense in spending top dollar for the latest when you can get the previous generation for a much more reasonable price.

Knowing that, it isn't surprising to see that the first thing Swappa noticed when the Galaxy S6 was announced was a drop in sales. Much in the same way early adopters are waiting with baited breath for the Next Big Thing, secondhand shoppers know the price of the current generation will come down as users try to sell their hardware quickly to offset the cost of the new phone. More people selling at the same time means competitive pricing, and that's exactly what Swappa saw with the Galaxy S6 launch. According to their tracking, Galaxy S5 sales increased by 30.87 percent while the average sale price dropped by 6.86 percent during the month Samsung first started shipping the Galaxy S6 to their new owners.

Both Swappa and eBay agree that the best time to sell your phone is before the new one arrives.

That's what happens when you sell in an environment filled with enthusiasts and early adopters. When looking at eBay's figures, things are a little different. According to eBay, Galaxy S5 sales increased by 65 percent in the 10 days following the Mobile World Congress announcement, and with that increase in sale volume came an average sale price increase of 30 percent. This bubble quickly burst and the sale price continued to drop after those initial 10 days, but it shows a clear difference between the way users are shopping and selling on the two services. People looking to buy a phone on eBay went looking as soon as the new phone was announced, while those looking for the best deal on their year-old phone waited a bit and hit up Swappa.

The big downside to selling your phone on eBay the day of the Galaxy S7 announcement is not having another phone to use until the new phone has arrived. Both Swappa and eBay agree that the best time to sell your phone is before the new one arrives, as the average sale price of your current phone will continue to decrease from now until release of the new phone. Swappa's data reflects a drop of 2-7 percent from the previous month just about every month a major phone like the Galaxy S6 is on Swappa, with some obvious fluctuations when other major phones are announced and users jump ship either to the Samsung Galaxy Note line or away from Samsung to something else entirely.

So when is the best time to sell your phone to offset the cost of the Galaxy S7? It really all depends on you. If your goal is to make the most money on your sale, you want to sell as soon as possible. You could wait until the announcement and try to take advantage of another eBay bubble, or take a look at what is available on Swappa right now and position yourself for a decent sale before the announcement. If you'd rather wait until the new phone is on your front porch or you'd rather try your luck with one of the trade-in programs from the carriers, you obviously want to wait. Either way, it's well worth keeping an eye on those sale prices to position yourself in the best possible place to make some cash.