Fitting semi recessed basin into worktop with overhang

[stratford_noob]

Hi,
I'm about to fit semi recessed basin into the worktop and we've decided we would like to have small overhang above the units (30mm to base unit = 18mm door + 12 mm overhang). So before I will do cutting I just wanted to doublecheck if my approach is right, as I only have one chance to cut it right obviously.
So logically I should move the template 12mm back so the fold line is in flush with the door/panel under the basin. After the cut I wanted to mark the contact point with the basin on the edge and remove the excess with hack saw like here

so the basin can slide in position completely (although what confuses me, is that he doesn't move the template back to compensate for the overhang).
Is this approach sound, or there is something I'm missing/should consider?

thanks

 

[Deleted member 174758]

Hack saw? For starters that's a coping saw.

 

[Ryler]

(although what confuses me, is that he doesn't move the template back to compensate for the overhang

I expect his over hang is so small that it doesn't affect fitting.
So move it back 12mm.