When I did mine, I first made sure that the clock position would not interfere with wooden frame that dash is screwed to. I also did pilot hole, reverse cut first and then forward. No cutting of veneer beforehand and it came out clean. Two things I found: the dash was something like 9 ply, and as the blade advanced, the glue in the ply got pretty warm and sticky and smoked a bit. Having finished the hole, it was a little too tight for the clock, so I use an abrasive flap wheel on a drill to open it out. Found plenty of length on the wiring loom.
