You need 75% cooldown to keep Ephiany up all the time. You can get into the 60's alone with skills and items. Googok of swiftness gives another 5% on your sheet and zodiac ring will get you the rest of the way. I keep 100% uptime on my zdps healer monk.
max cdr you can achieve as monk with the right gear is 78,52%, including gogok that goes to 81,74% thus allowing you to have perma epiphany but to get to those levels of cdr you have to put cdr on neck, use vigilante belt, born's 3 set and captain crimson's 2 set, not really usable aside from maybe some fringe zdsp build, for every other build obsidian ring of the zodiac and as much cdr as you can pack into proper gear will do the trick most of the time