Spot if needed for hole placement accuracy.
Drill with tap drill.
CS front in drill press.
Flip it over and CS on back.
Tap.
If surface must be absolutely flat, stone or file it to remove any raised ring.
On the CS, I usually go for a one thread depth. That can be adjusted if the material is thin but one thread deep is usually enough to prevent the tap from raising a ring above the surface. This applies to both front and back sides. It also helps in starting the tap in a centered manner.
I usually CS on the drill press where I have a good depth stop (note below). That allows you to easily and accurately adjust the depth and then all the holes are CS to the same degree. And if the back side does not have any raised rings, then the back side CS can be done with the same depth stop adjustment as used for the front side.
You also need to look out for how much of a raised edge is created on the back side by the drilling operation. If excessive, you need to run a file or stone over the back before doing the front side CS.
Note: At the present time I do most CS on my smaller, bench drill press. I have a depth stop installed on it that uses a push button nut which allows both rapid movement to a coarse setting and the fine adjustment of the screw thread. And it does not need to be locked with a second nut so it is real fast to use. In fact, I attribute all my use of the depth stop to this "magic" push button nut. Before I had it installed there, I almost never used the depth stop. The push button nuts are a treasure.
One more note: I countersink before tapping because I have found that doing the CS after tapping will distort the first thread in many of the softer materials, necessitating a second application of the tap. If you CS first, this almost never happens and you wind up with a perfect thread with just one application of the tap.
