"Currently, there is no set date for the beginning of the transition period, but the best estimate would place the time frame somewhere in the middle of June. "
The update is here:
https://blogs.secondlife.com/community/features/blog/2009/06/01/adult-content-changes-in-summary
The steps needed to take are listed here:
https://support.secondlife.com/ics/support/default.asp?deptID=4417&task=knowledge&questionID=6345