I believe if you follow the plans order you will have to put the manufactured head of the rib flange rivet on the forward side of the spar. I'm sure that's perfectly acceptable, but I wanted to keep all my rivets facing the same direction. Plane should fly faster that way
If I recall, there was one rivet that was a little difficult if you attach the torque tube assembly to the rib after rib is already installed.
Pictures and process I used in the "Wings (primary structure)" section of my blog.