I also measured and marked the borders before attaching them - I either used straight pins or a chalk pencil.
If I was attaching this to 12 inch blocks, I would mark the border at 12 inch intervals, etc.
When I just sewed a border on, it tended to come out unevenly.
I have learned so much the hard way. So now I spend a few extra minutes in preparation and save myself hours of unsewing and resewing.