Prehung Door Question
The standard jamb is 4.5 inches and is based on an assumption of .5 drywall on each side (.5 dw + 3.5 stud + .5 dw).

When a different thickness of finish material is being used, custom jambs can be ordered or constructed onsite. If you use standard prehungs with conventional widths, you need to create a jamb extender.

The simplest way is to install the jamb flush with the finish material on one side and attach the extender to the other side. You can use a trim strip, such as a flat lattice piece or other thin material around .25 inch thick. It can be glued and tacked to the edge of the jamb. 

While you could try to get the extender exactly flush with the edge of the existing jamb, such joints are rarely exact and tend to leave a seam, even if filled. Most finish carpenters do not try to do exact aligns, but use a reveal, a slight offset that looks intended. In this case, move the extender trim about .125 (1/8th inch) away from the door opening, toward the drywall. Glue and tack. Once painted it will add a detail that enhances rahter than looking like a fix of a mistake.