I just step drill the bar first keeping track of what drill size I use and how deep I go with it then turn it to shape being careful not to cut into the drilled step shoulders (thinnest after turning at the shoulders).
I helps me to draw a sketch of it before turning with the correct dimensions listed for the steps so I can measure my progress and avoid accidentally cutting too deep. More important to do this on a ball point type pen than a fountain pen since the final point and hole are much smaller than the hole for screwing a FP feed into and I need to have the right diameter and depth for the spring. At least it is for me and I admit I'm a very amateur pen maker and don't make many since it is only done for my own pleasure when I do.