Framing Exterior Long Wall in Sections
As Ed's comment said, you can still do all of the sheathing on the ground, you'll just end up having to nail one stud once the wall is up. 

Rip one sheet of plywood at 16 inches, and start from your layout end with that. That will provide you 16 inches overlapped onto the second wall section, and the 32 inch cutoff piece should finish the second wall out. Try and keep it all as flush as possible with the wall ends so you have a small gap between the overhanging piece and the second section's first piece, it probably won't line up exactly and a small gap means you won't have to trim it once the walls are up. 

On the other hand, you don't really need to lap the sheathing. When you layout your studs, put a stud at each end of both 12' sections. Once you raise the walls, nail the two studs in the center (at the end of the wall sections) to each other. Run the top top-plate at least 2 feet onto either wall.