Strong demand and five million sales (perhaps even more) during the opening weekend continue to put a strain on the initial iPhone 5 supply. If you’re in the market for an iPhone 5 and are an avid Apple fan, there’s a reasonable chance you’ll want to waltz inside one of Cupertino’s shiny retail shrines. After all, a new iPhone is a once-in-a-year event so why not treat yourself to that talked-about buying and ownership experience, right?

The problem is, the iPhone 5 is hard to come by at the moment, even as Apple is regularly stocking stores. Luckily, there’s now a better way of buying the sought-after device involving a simple online pre-reservation for in-store pickup the following day…

It’s a huge time saver: no longer do you need to drive to the nearest Apple Store every day to check if the iPhone 5 is available.

The word on the street is that Apple will begin taking online pre-reservations in the U.S. and UK starting 10pm tonight, for the following day. I’d download and install the official Apple Store app as it greatly simplifies the buying process.

Note that your mileage may wary because pre-reservations depend on daily iPhone inventory.

If the system won’t accept your pre-reservation, try again the next day or the day after.

Another thing to keep in mind: pre-reserved devices must be picked up in-store in the next 24 hours.

Otherwise, your order will be cancelled and the company will issue a refund.

Sebastien was able to officially verify the news with an Apple specialist and just snapped the above shot at the Apple Store in Carlsbad, California.

The sign reads:

Due to the popularity of iPhone 5, limited quantities are available for walk-in purchase.

You can also visit after 10:00 p.m. to order one for pickup in store.

For more details, talk to a Specialist.

For now, Apple’s retail page still says that iPhone 5 purchases are available on a first-come, first-served basis:

Now available for walk-in purchase on a first-come, first-served basis at your favorite Apple Retail Store. We can help you choose the right rate plan and get you up and running.

Over at the UK Apple Store, however, the retail page reads:

Reserve yours now and pick it up in store. Limited quantities are also available for walk-in purchase on a first-come, first-served basis. Either way, we can help you choose the right tariff and get you up and running.

According to our little poll, the vast majority of respondents pre-ordered their iPhone 5 and had it delivered to their doorstep.

Apple CEO Tim Cook said in a media release announcing sales of five million iPhone 5 units:

While we have sold out of our initial supply, stores continue to receive iPhone 5 shipments regularly and customers can continue to order online and receive an estimated delivery date. We appreciate everyone’s patience and are working hard to build enough iPhone 5s for everyone.

Not sure about you, but I’d rather deal with humans as little as possible so in my view, pre-reserving stuff is always the way to go.

Plus, it’s both a time saver and convenience.

Besides, you get a nice excuse to visit an Apple store.

And you?