Less than 24 hours after the new iPad was unveiled and put up for pre-sale, some of its models have already been delayed. In terms of shipping dates, some 4G enabled models on AT&T’s network have been pushed back three days.

Over at the Apple online store, it appears that the biggest demand so far is for white 4G enabled models. Both the 16GB 4G model ($629) and the 64GB 4G model on AT&T show a delayed shipping date of March 19th. As you may recall from our coverage of the iPad event on Wednesday, Apple said they would be releasing the new iPad on March 16th.

And that’s still the case for all of the other models as of right now. All of the Wi-Fi only iPads as well as all of the models on Verizon are still showing March 16th. And all of the black 4G models on AT&T are also still on schedule.

Of course, this is likely to change at any moment, as anxious iPad fans flood the online store with pre-orders.

March 16th is a big day for Apple, as they will launch the new iPad (yep, the “new iPad”) in 10 different countries including the U.S., Canada, Australia, and Japan.

The new iPad sports a 2048×1536 Retina display and an all-new quad-core A5X processor. It also has a new iSight camera and voice dictation. With the launch of the new iPad, Apple also brought iPhoto to the device along with officially launching iOS 5.1.