I think I have narrowed the time frame down enough to satisfy my curiosity. I found another old photo in Verla's collection that shows New Harmon in 1928. It looks pretty well established by that time, so they must have been in the process of moving at least a year before this picture was taken. I am reasonably sure that the move started sometime in 1927 and was pretty well completed by the time this picture was taken. The trees aren't leaved out, so this was taken either in the spring or fall of 1928. I am guessing it was early spring.
This picture is looking eastward from a point just in front of my grandparents' house. The large building on the left side of the road is their store and the hip roof just beyond this is their service station. Louie Dumbauld's cream station is the first building west (toward the camera) from the Richard store, then Frank Wieden's barber shop and the Parkman Phone Company Central Office buildings are nearer on the same side. On the other side (south side of the road), the big building is the Odd Fellows Hall. I don't know for sure, but I think the other building on that side is the Diamond family's filling station. The post office was built later, on down farther east on the right side of the road. Then Guy and Veva Ward bought the vacated Baptist Church that originally sat up by the cemetery. They moved it onto the northeast part of Harmon. That would be in the far background on the left side of the road.
You can see the town water system windmill over the top of the Odd Fellows Hall. That well was on Albert Wright's lot, where he had his blacksmith shop, but I don't see the blacksmith shop. It may be hidden behind the Odd Fellows Hall. They actually had movies in that hall for several years.