Yep, as above - you can just see where the sleeve (ground) is connected to its respective lug.
With TRS plugs, generally speaking the lug will be directly across from the corresponding plug/contact. You already know which one the sleeve is, so the tallest contact (tip) will have the tip lug directly opposite it and the middle contact (ring) will also have the ring lug across from it.
And of course you can also just look at the wafers, too. Just follow the tip contact down and see where it "enters" the fiber wafer. The corresponding lug will naturally come out of the same "level".
But I get it. For whatever reason I always am forgetting or spacing out on it too, so as was said above also I usually just plug in a cable and use my multimeter if I'm doubting for some reason.