Conrod balancing

After removing some material from the big end would I weigh the conrod 5 times to work out an average like the first step or is it ok to take the enitial weight after removing material and stick with that measurement?

It's going to come down to the repeatability of your conrod weighing fixture. If you tend to get good repeatability from one weighing to the next then there's no need to weigh the rod multiple times. Some fixtures provide a little friction which can affect the recorded weight and this makes it harder to get repeatability. once you're familiar with your specific equipment you'll get a feel for what you need to do.