Just prior to the heavy holiday shopping season, the shipping time for orders placed from the online Apple Store was 1 week. Besides the heavy demand for the 7.9 inch tablet, some of the suppliers were having problems delivering parts. For example, one of the companies that provides the display for the tablet, AU Optronics, was having a problem with low yields. This reduced the amount of finished product that Apple could sell. AU Optronics said that normal yields would resume in the current quarter.
Apple CEO Tim Cook, as recently as January, confirmed that suppliers were to blame for the shipping delays, as they were having problems meeting demand. Cook said that things would be back in balance by the end of the March quarter. But now it would appear that supply and demand have reached a balance earlier than expected. Shipping time has been now dropping continuously from the one week in December, to 3 to 5 business days in January, to the current 1 to 3 business days. You can't do much better than the current shipping time.
source: AppleStore via AppleInsider