Where does “jį́įgo” come from?

jį́įgo (Navajo) comes from Navajo jį́, from Proto-Athabaskan *džʷeˑn.

Ancestry of “jį́įgo”, step by step

Step	Language	Word	Meaning
1	Navajo	jį́	day
2	Proto-Athabaskan	*džʷeˑn	—