Here are my 2 cents on the Status changes:
The Applilcation status remains in "Application under review" as soon as they have verified that all your documents are present.
Status description (when you click on "status report" on the main screen) is what changes and this will give you an idea as to when exactly the adcom guys start reviewing your application.
Stage 1: The description reads something like " Your application is ready for review......" and under additional notes they put in comments if they will need your official transcripts etc at a later stage if you are invited for interview
Stage 2: When the adcom guys actually pick your application for review, the status description changes to this -
"Your application for admission to the Berkeley Full-time MBA Program is under review by the Admissions Committee. You will be contacted at the decision deadline to see your final admissions decision"
Once your status description changes to this, you can start looking for an interview invite. Now, nobody knows how long it takes to get interview invites after Stage 2. Some got it in a week, others even longer..... probably based on how may hands your application passed through or based on availability of an alum for interview etc etc.
So all of you whose status description reads like whats mentioned under stage 1, do not panic until you reach stage 2.
others under stage 2, hope for the best!!
Mine is in stage 2 from 18th and I am in a panic mode right now.