Just use 2 axis contour to machine the hole, after you chain it, select "plunge" from the top toolbar and select the holes center. This will allow the cut to start at the center of the hole.
If you have several holes and do not want to select each center point, use the Lead in move, and set it to Line on all, the change the lead in length to the holes radius. You will need to set the leadin amount from "tool radius" to "constant"
As far as overlap, I guess your not using truemill, since this feature has an "overlap" amount, If your using contour, then the best way I know is to use the Lead In/Lead out controls to build in overlap.