I feel like cdr at the begining for nasus just dont helps you as much as u would thought. Why? Now a full core build in nasus has already the 40% cdr. Just dont go with Runes Cdr because it just dont worth it anymore you rather have more magic resist/armor it helps you sustain more in lane or instead Quins Cdr take life steal quins.

Hate to break it to you but I just laned vs Fiora, and that ***** is crazy, she does true damage so she really doesn't scale badly vs armour and she totally trashed me. Not just cos I'm bad, that is literally the worst matchup I've ever had, I've beaten teemo with Nasus. So you may wanna change the matchup advice.
Edit: I've just done some reading on the lass, she does magic damage, physical and true damage, and heals from attacks. So is like nasus, but more mobile and more OP.