you must be close to him (I'd say just a bit closer than your auto attack range) tho or aim before he even cast Q since your Q animation from max range will travel a lot slower to Nasus than Nasus auto hitting the minion, not to say blinding him will attract agrro of enemy minions which will make your cannon alive more if you are not perfectly positioned, not bad to max Q against him just to delay as many stacks as possible but that will not guarantee you win against him if he can stall enough or even get jungle assistence.

it's the most common rune I seen to be used on him, is good enough for some trades since you will probably don't kill anyone in lane phase just by proccing it, and since now the top meta have a lot of ranged champions you can't really free proc electroc without giving a chance to trade back.
For example let's say you want to trade with Kayle, she will just E you and go back probably, procing her klepto and you get nothing in return.
So if you are not playing against Kayle, Urgot, Mundo(Mundo cause is kinda useless to proc electro on him, is much better to have something like grasp, or aery) and some more few examples it can work good. Also you can insta proc it with aa gunblade Q which is pretty good again.
But personally I just prefer harvest overwall insead of electro so that would be the main reason I dont have a rune page for it in guide (and cause most guides alerdy are spamming electro everywhere)

thanks and sorry to read it so late lol.