The goal of this build is to capitalize on jhin's synergy with The Collector, and the bounties runes to get item quickly before the enemies build enough resistances and dmg to fight you. Mythics are bait items on Jhin so you should not rush a mythic first in any cases and should only get them as a replacement for boots as a last item.

Using this build, I am usually full build around 30 minutes while 2-3 tapping almost everyone on the enemy team