I did my template on the computer, but left my holes, until i knew which straps, handles and fins i was going to use. Most are interchangeable, but have found some brands are different.
I.e. Some fins use one hole some two.
Some handles are a fixed distance, some, allow a 10mm tolerance.
Footstraps, binding plates offer various distances.
I have used 6 x inserts for my board, but if i didnt have my hardware, i could of used 12 inserts.
My best advice, use another board as a template for holes, but make sure you know which fins, straps etc you are going with, so you dont have to put unnecessary holes or fixings in.