In all the times I have played through, (at least a dozen), I have never found the yagluth location stone, prior to finding the altar. I always end up seeing the "hand" from a great distance.

On my latest playthrough, I saw the altar (as usual) from a distance, and walked over to it... Moments before arriving there, I stumbled onto this....

https://steamcommunity.com/sharedfiles/filedetails/?id=2860212327