Should be fine. The pump doesn't really pump that much oil.

As long as it's an even amount coming from each line all will be good.

I run premix because when I did a manual test of the oil pump, 1 line had twice as much oil coming out as the other. I probably could have flushed the pump with diesel but I don't mind premixing as it's just a toy and not a sole means of transport.

If it makes you feel better, run on premix until it's all green but i doubt it would matter. You won't be thrashing the motor on run in anyway.

Andy