a few other points
if you cut out with a jigsaw about five or 6 mm inside the line
you will be able to cut with fewer passes of the router
cut in a clockwise direction if you cut anti it will push away from
the guide
cut a dummy out of ply the hold it over the sink if its wrong
you can adjust the template
also exagerate the curve on the template it will be slightly less
on the worktop
support the top evenly on both sides of the cut so there is no
strain on the point your cutting[ssssssssnnnnnnnaaaaaaaaapppppppp]
what material is your wotktop and how thick
you may need a longer cutter the cutter should be inserted
with two thirds inserted into collet [chuck]
what size is your router half inch or quarter inch 6mm or 12mm
and dont let your old man exagerate the size of his tool