Will moving your optics one notch forward on the top rail take it off zero?
Possibly.
What kind of optic - we talking an RDS or a precision scope?
I’ve moved my Aimpoint around on the rail experimenting and have had no discernible issue. I’ve also accidentally mounted my 4-14 in a QD mount into the wrong T-Slot and had elevation discrepancies.
There are a lot of variables including type of mount and how it affixes to the flattop, as well as any built in MOA inclinations for the mount, and repeatability of the mount itself…
It’s an Eotech 511. Looking to move it one position forward towards the end of the receiver, from its current seat seen on the pic below.

I would say it quite possibly could. Just move it and invest in firing 5 rounds to re-zero if needed.
did for me, I did the same mounted my eotech as far forward on the upper as I could so the battery compartment hangs over the handguard. Looked like yours originally so two or three slots forward.
I don’t remember up or down but few shots down range and it was game on.
sorry i just went and looked I have a 516 so mine was originally in the same spot but I was able to mine much farther forward then yours will go.
why i should leave tech questions to the pro’s.
I’d move it and shoot it, that seems to be the safest way to figure it out
Thanks! Ya, will do. I was just hoping I wouldnt have to zero it before the next session which most likely wont be any time soon.
Is the optic currently co-witnessed with your irons?
If you can line up the irons and have the dot sitting on the front site post in it’s current configuration, see if it still does so in the new configuration…
And then go confirm it with live fire, of course. But it’s a pretty reliable indicator…