I think anything above a two-gun mount is very unlikely, and even that's pushing it... and they wouldn't look like British late 1920s-onward six-inch turrets. The only case of a turreted six-inch gun from before the '20s I know of the top of my head is the Swedish 152 mm/50 Modell 1903 and 1912, and they were mounted mainly as secondary weapons on CDSs(The Modell 1903 was mounted on the armoured cruiser Fylgia from 1907 as the main armament as well), not to mention Sweden was one of the biggest pioneers when it came to turreted secondaries(In this case, 6" guns), the first class to mount them being the Äran class, commissioned in 1902.
Below is a photography of the HSwMS Gustaf V, showing off the Model 1912 in the smaller turrets.