I was hoping to see The Beach Boys - Kokomo

A picture would be worth a thousand words. Usually when you remove the putty and glass it’s pretty obvious where the new glass rests. Can you take a pic?

I restore historic windows and cut glass every day. You need to provide a little more info. Usually the glass fits in a rabbet in the wood sash, so there is about 1/4” wide flat channel for your glass to rest on. Your advice to measure and subtract 1/16 - 1/8 is right but I feel like you’re not quite getting it.