If by smoking you mean cooking the sausages with smoke to an internal temperature of 150* or so, about 10 to 12 hours should do it. Smoker temps are around 160* to 170*F. That is not fresh, but has to have nitrite cure included in the spice mix.
If you mean cold smoking for flavor, but still not cooked, I do mine about 4 hours. But it still gets nitrite cure added to the spice mix. Smoker temps reflect the heat generated by whatever method is used to generate the cold smoke. I like to see mine running around 70* to 80* F.
In both cases, it helps to let the stuffed sausage hang at room temps for a couple hours or so to dry out the casings. They don't take smoke if the casings are not dry.
The danger when smoking is botulism poisoning. The spores go active and start producing poison when temps are between 40* and 140* F in combination with a moist, oxygen free environment. Exact conditions found inside a sausage smoker when cold or hot smoking sausage. Nitrite cure stops the spores from going active. You don't smoke sausage without it.