Remember also to fill the pipe from pump to inlet rubber with oil.

The way to check if your oil pump is working is to put a small amount of premix in the tank and run the output end of the oil pump into a small bottle taped to the side of the crank case. Go for a short run and you should find significant oil in the bottle.

If it's working this should be good enough. If you want to know if it is working properly you need to work out how much petrol has been used and how much oil. There are so many variables in measuring such small quantities of liquid and how much throttle and load that this is almost impossible to be accurate.