Step 1- a sharpe automatic punch on the layout intersection;
Step 2- then a small punch on an angle if some lateral adjustment is needed (like others described above); and
Step 3- then a healthy wack with a large punch to give the drill bit somewhere to bite in.
Step 2 is optional.
Today i ordered some acrylic dowel from Amazon. An optical centre punch is going to be a project when the dowel arrives. Hopefully this new tool can take me right to Step 3.
I think getting the crosshairs accurately onto the flat bottom of the dowel will be the biggest challenge. (Oh yea, I only have a mill - so getting my mill to think like a lathe maybe a challenge too).