Also, plan to install vertical support framing at one or more points, consistent with future use of the area under the stairway. If you plan to add sheetrock and/or skirt boards, place a spacer of equal or greater thickness between the stringer and any adjacent roughed-in walls.
Bracing & Blocking
An important consideration for a sturdy installation is to install sufficient bracing at key points in the rough carriage. Points at which newel posts will be mounted, where rails will terminate or where outside skirt boards and decorative trim will be applied should all be carefully framed and reinforced at this stage (as seen below):