Plan on hobbyists on Saturdays. Correct MC is the key to repeat business. Advertise locally and be prepared to ship pieces to schools, small shops, etc. Planed lumber will sell much faster than rough. If you get a moulder, your business will probably double.
Marketing is another key.
Gene Wengert, forum technical expert I have owned and run a retail store for 10 years. We have consistently sold door jamb, casing, stop, custom millwork, and S2S 1 x stock. We are a small operation and our door parts and millwork are solid high grade material, versus the finger jointed stuff sold by the big box stores. For years we bought rough sawn from the local sawmill and recently graduated to sawing and drying our own lumber. Don't overlook the rehabber market if you are in a big city.