How long grinding the edge of a stone axe takes is to a great degree determined by the quality of your abrading stone. Mine happens to be very good, so the process is quite fast. When I abrade edges on stone, I usually start by making a "half" bevel. That is, I start grinding the sides first, more or less to the angle I want the bit of the axe go at in the end.
When I have done that I start grinding much more steeply to even out any dips in the front. In this particular piece there was a rather deep flake scar in the front from testing the blank's integrity.
When the edge is totally even, the most timeconsuming part begins. Narrowing the bit to a usable bevel takes quite a while. Work systematically and if unmotivated, take a look on the progress. I think you'll be surprised of how quick it really is. I used only about 1,5 hours on the bit of this particular axe.
The last task on this piece is to make the handle. A task I fear will take longer than all of the stonework combined.