Preview at WWDC likely in June, followed by September launch.
Average Wait Time for Mac App Store App Reviews Rising Significantly
Shiny Development's annual trend graph for Mac apps shows average review times of a few days to a week through approximately April 1 of this year, after which time the trend began a fairly steady rise. That rise has accelerated in recent weeks, with developer reports now indicating that their apps are spending an average of nearly a month in review.
The sample size is admittedly small for Shiny Development's Mac App Store calculations, with 62 reports having been collected over the past 30 days, but the firm reports that the data is generally fairly indicative of broader trends in their experience.
The averages on this site are based only on the data gathered from Twitter which are a very small subset of the total number of apps which go through review each day. However in our experience it does give a reasonable indication of how review times are changing over time.The trend for iOS apps is less severe and is based on more substantial data as would be expected for the larger iOS App Store, with 471 data points being included from the past 30 days. Average iOS App Store review times have been within a range of 3-11 days over the past year and currently sit at one week after declining from their peak roughly two months ago.
Developers interested in contributing to the project can find tweet their waiting times using the respective #iosreviewtime and #macreviewtime hashtags, and Shiny Development offers a few guidelines on how times should be calculated.