Your cutter mark goes past the base of the ferrule. Stop right where the ferrule ends just undersize of the wood. Finish sand the wood between centers after you tip it, light with 220, then strong with 400. The wood sands away faster then the ferrule. You're taking a chance of necking the wood down trying to get rid of your cutter mark.
Sand the outside of the ferrule with 220, then 400 before tipping. Otherwise you carry tip dust into the ferrule that your can't get out.
VERY good point on your collet slit needing to be between your 3-jaws. You need your runout around 0.001" before cutting the ferrule flush. I like to clamp the shaft tight in my back collet wrapped in a piece of 1/16" rubber gasket material. Then clamp it tight in your front collet wrapped in a smoking paper. I can never get the runout I want using a split collet. Yours looks pretty accurate though.