When I'm cutting out parts, here's my method for doing comp using AutoCAD. Pick a corner of the part where you want to start and stop, and extend those lines a little more than 1/2 the tool diameter. Then I add the leadin move to the start. I use the leadin to ramp into the part, and since I work with wood, I find that an 1-1/2" long ramp works pretty well with a 1/2" tool. I try to keep in in line with the part profile, offset to the side by the radius, which will actually let the tool enter the stock on a fairly straight path while the comp is being applied.Then I add a leadout move, where I ramp out of the part, which prevents a dwell at the end of the cut which can dull the tool a little bit. I use a macro that I wrote for AutoCAD that exports the g-code directly from AutoCAD, with the G41/G42 code and ramping automatically applied.