My Suggestions

Iyo2

adv. · day before

  1. Day before yesterday

Example: "Nyũmba ĩyo njerũ ĩkahakwo rangi mwerũ jumamothi." — That white house was painted white on Sunday

ĩyo1

n. · class 5/6 · day before yesterday

  1. day before yesterday; o ĩyo-ĩyo = just the other day, very recently, a couple of days ago; ĩyo rĩũ rĩngĩ = three days ago; ĩyo rĩa ĩyo = four days ago