Determining whether the oil burning is the result of rings or valve seals cannot be done by symptoms. Both will produce oil smoke when idling, both will do so on decel, neither as much when the cylinder pressures are up.
Remove the valve cover and look through the springs to see the valve seals. If they are present, and straight, then its not the valve seals.
It will be the rings, as the surface finish of the cylinder walls and the type of piston rings used can cause the greatest variables in engine building. Valve seals are a no brainer by comparison. B18's didn't even use a stem seal, and they didn't burn oil at a stop light.
Pull the plugs. If one is oiled more heavily I would suspect a mis-assembly of the oil ring expander. If all are oiled or the same, then cylinder wall finish.
Check your crankcase breather, just in case.
It is not normal for new rings to produce oil smoke. Any machinist that claims it is, is no machinist.
It may be that further driving will seat the rings, but if it is one cylinder at fault, the engine will have to come apart.