Fill the oil tank completely, and disconnect the oil input line at the oil pump to bleed off the air in the oil filter and line by gravity. Keep the oil tank completely full for best effect. Then reconnect the oil line at the pump.
Run oil in the oil tank during break-in _and_ 25:1 premix oil in a 25L fuel tank for the first 1 or 2 tanks of gas. Initially, the oiling system will not be providing oil, because of air in the lines, so your start-up mix will be the 25:1 from the gas tank.
During that initial run, the oiling system will push air out of the check valve, and start delivering oil into the carb system. If you use up the 25:1 gas by about 10 hours, you can go to 50:1 premix for the next tank of gas; by that time, the oiling system should be purged of air, and delivering oil. You will then be getting both the automatic oiling (at about 50:1 for medium speeds) _and_ the premix fuel at 50:1, so your resultant oil ratio will still be about 25:1.
After break-in, run straight gas in the fuel tank, keep the oil tank near full, and you are good to go.