To inset the aprons 3/4" from the outer surface of the legs I made a spacer from 2 pieces of plywood.  This little jig made it easy to keep the distances uniform and also secure the apron to the leg while fastening.  Pic 3 illustrates how the jig, apron and leg are clamped together for fastening.  Each apron end is held by three 2 1/2" pocket screws.  The pocket holes were made using a Kreg pocket hole jig.  I assembled the short ends first and then the rest of the table base making sure the kerf (for clips) was along the top edge.  Since this is a long table I also added a cross piece in the middle of the table using pocket screws.