|I'm currently in a shirt-making phase. The last four patterns I've looked at/made, all have the button bands sewn on to the front first, then folded over and slip stitched to the back. Slip stitched.
There is no need for this. Here's what I do and will always do. Fold the button band in half lengthways and press flat. Now sew the button band to the back, first. Press seam towards button band and trim off a bit of seam allowance (to make room for buttonholes, later). Flip over to the front. Fold front seam allowance under, but not 5/8", make it a tad less. Press flat - you're on the front of the shirt now. Open up again and insert a single layer of fusible web tape. Close and iron shut.
Now the free edge is on the front, where everyone will see it, closed with fusible tape so it won't move under the machine. The edge is 1/8" away from the back seam, good. No one can see the under seam on the top of the shirt.
Edge stitch both sides. Perfect.
No Slip Stitching.