It’s easier to measure from the back and I start from the wall one speaker at a time using the Sumiko Master set method, unless the speakers are designed for boundary use.
Pay attention to levelling unless measuring at the bottom.
Different wall construction also has an effect. With Naim NBLs, a boundary design, and a solid, render on brick, wall they gelled at 5.5cm. The same worked in an apartment with concrete walls but moving them to a house with dry lined walls saw the out to 33.5cm to bring them to life. This is around 78cm from the front baffle but it’s harder to be precise. I was pleasantly surprised they worked here st all and had started auditioning replacements before even trying them.