If you're tempted to go out and buy an Apple (NASDAQ:AAPL) iPhone 7 or iPhone 7 Plus right now, then I have some advice for you: Don't do it!

Of course, if you absolutely need to buy a new smartphone right now, and waiting just isn't an option, then either the iPhone 7 or the iPhone 7 Plus is great and will serve you well; the iPhone 7 Plus is the best smartphone I have ever used. 

Apple's iPhone 7 and iPhone 7 Plus in Product RED.

Image source: Apple.

But, if you can wait just a little longer -- I'm talking about maybe a month or so -- then I highly advise that you do so. Here are three reasons why.

Today's iPhone models are about to get cheaper

If you're convinced that the iPhone 7 and iPhone 7 Plus are more than enough for your needs, then great! I still don't think you should go out and buy one -- at least not at full price -- right now.

When Apple introduces its next-generation iPhone models within what is almost certainly going to be a month, it's likely to discount the current iPhone 7 and iPhone 7 Plus smartphones by about $100.

If you wait until the new models are announced to buy your iPhone 7 or iPhone 7 Plus (assuming, of course, you don't find a great deal between now and then -- if you can, I'd say "go for it"), then you can save some money.

$100 might not seem like much, but invested wisely, that $100 saved today could grow to be multiples of that in the years ahead.

Tomorrow's iPhones will improve value for your dollar

If you're not interested in saving a little bit of money on your next iPhone purchase, waiting just a little longer will allow you to get much more for your dollar.

In addition to the premium-priced iPhone that everyone seems to be talking about, Apple is expected to launch two relatively straightforward successors to the current iPhone 7 and iPhone 7 Plus smartphones commonly referred to as the iPhone 7s and iPhone 7s Plus.

These new phones should be similar in form factor to the current iPhone 7 and iPhone 7 Plus, but with a whole host of internal upgrades such as a faster A11 Fusion chip, True Tone display technology, and the addition of wireless charging.

Additionally, the phones are expected to have glass backs and metal frames rather than the current aluminum unibody designs of the iPhone 7 and iPhone 7 Plus, potentially making them look more premium than the current models.

I also wouldn't be shocked to see improved camera capabilities, too.

In terms of pricing, I expect that Apple will price the iPhone 7s and iPhone 7s Plus similarly to the current iPhone 7 and iPhone 7 Plus, so your dollar will go further if you can just hold on for a month or so.

You might want that premium OLED iPhone

Even if you think you're cool with today's iPhone 7 or iPhone 7 Plus phones, or you think that you don't want to spend any more on an iPhone tomorrow than you would today, there's a third reason to potentially hold off: the OLED iPhone.

The OLED iPhone is expected to be completely redesigned. In addition to the glass back that the iPhone 7s and iPhone 7s Plus will likely have, the OLED iPhone is also expected to include a large, full-face OLED display in a footprint that's more compact than the iPhone 7 Plus's (and, by extension, the iPhone 7s Plus's).

It's also rumored to have facial recognition technology, enabled by a new 3D sensor built into the device.

At the end of the day, you might decide that the OLED iPhone isn't worth the premium to you, and you might ultimately opt for a price-reduced iPhone 7-series device or a mainstream iPhone 7s-series device.

But I do think you owe it to yourself -- if you're thinking about buying an iPhone today -- to wait until the new models drop before handing over hundreds of your hard-earned dollars to Apple for an iPhone, if circumstances allow you to. 

Ashraf Eassa has no position in any stocks mentioned. The Motley Fool owns shares of and recommends Apple. The Motley Fool has a disclosure policy.