You might want to run a few patches down the chambers and bore with your favorite smokeless powder solvent. Other than that, I would just shoot it.
You can get a good idea of how much any revolver has been shot by inspecting the recoil shield. Every time it is fired, the cartridge head slams back against the recoil shield under recoil. Eventually this will wear the blue and leave what I call a 'halo' on the blue. In addition, the unfired rounds in the cylinder will also slam back against the recoil shield as the gun jumps back and the rounds slide back against the shield. The halos made by the round being fired, will always be more prominent than the halos made by the other rounds in the cylinder. It will not give you an accurate round count, but it will give you an idea. This K-22 shipped in 1932 and it has been fired a great deal over the years. By the way, I consider this to be a Vintage revolver.
This K-38 shipped in 1957. It has not been fired as much as the K-22.
This 38 M&P shipped in 1908. It has been fired less than either of the other two.
Again, don't try and guess the round count with this method, it will just give you an idea of how much it has been shot.
From your photos of your 18-3, it looks like it has been played with a lot, because the blue is completely worn away around the center of the recoil shield by opening and closing it a lot, but I don't see much in the way of halos.