Wait until day 5-7 before you even try baking. Most storebought flour doesn't have the wild yeast you need right away. Mine was completely dead on day 3, then on day 6 it started bubbling like crazy after I switched to half rye flour and half all purpose. Rye has more of the natural yeast on the grain so it kicks things off faster. Also keep it in a warm spot like on top of the fridge or near the stove pilot light. Cold kitchen slows everything down and you end up with a brick.

Start by timing how long you spend dimple-filling - I bet you could streamline the process by mixing the compound a little thinner so it flows into the holes instead of needing extra muscle to press it in. That trick alone shaved about 30 minutes off my last board-hang when I tried it, and the finish still came out flat without any extra coats. Doesn't the time saved make the initial prep worth it even if you're only cutting down one coat?