Prior to fletching, I'll spin the shaft on the Pine Ridge Arrow Inspector and then use the ASD to shape up the ends of my arrow. Sometimes an arrow after it is cut will have burs that should be removed prior to inserting an insert or nock.

Then I will glue in the insert and insert the nock.

IMO you must have your nock end as square as possible before you fletch. I have seen individuals cut arrows, insert a nock and use a fletching jig only to have poor results. (aka mis-aligned vanes due to the mis-alignment of the nock into the shaft)

A square nock will ensure that your arrow sits properly in the fletching device.

Best of luck!