Crank it a little longer after the oil pressure light goes out. Oil pressure light shows pressure is building, but it triggers rather low. I've got an oil pressure gauge and cranked it a little longer, before pressure really got up. Just 10-15 seconds if I remember correctly.
I'm in still running in my new engine, which essentially means being a bit careful. There seem to be two ways of doing it, the floor-it method and the gradual one. The first is based on the argument that the rings extend a force on the liner due to the compressed gas. So if you're not putting the engine under load, the rings will hardly bed. The idea is start the engine, warm it up and gradually go to higher and higher RPM in a couple of runs and let the engine cool in between. Full break in should be done in 30-40 km. The second method is what you used to do with new cars, start out with low RPM's, vary speed, not too low in RPM and only after some decent mileage, fully load the engine. I did it the first way, as it's more fun and JE (I have JE pistons) recommends it: https://blog.jepisto...ak-in-an-engine. Not only new pistons, but a new engine with specially made liners. For that reason, I used Millers CRO oil for the first 100 km, then changed filter and oil. Now on Mobil 1 0W-40 for the next 1000 km and will change oil and filter again and consider it ran it after that. That's probably overdoing it 
