Sales were scheduled to start today (Wednesday), but have now been put off until February 18.
Opera house officials blamed the problem on late delivery of stage equipment and the need to take time to train the personnel in use of it.
The gala opening on April 12 is expected to take place according to plan.
Meanwhile, it was revealed that only 200 tickets for the 1356 seats in the opera will be sold to the general public for the grand opening. The rest of the seats are reserved for royalty, government officials, architects, sponsors, etc.
The opera house managers have decided to hold a lottery for the 200 exclusive tickets. They said that, given the extreme interest from all over the country, that would be the most "democratic" way to do it.
The ticket prices, at NOK 1490 (almost USD 300), have apparently not put off the public. There are also a small number of "standing" places available for about half the price.
Renowned Norwegian architecture firm Snøhetta has designed the ambitious opera building, which has been constructed in a minimalist style with a strong focus on acoustics.