on the morning i henna:

i always wash my hair, ACV rinse, then i do the dreaded DETANGLING in sections with loads and loads of conditioner, braid up, rinse, towel blot, take down each section, lightly seal with EVOO, comb with a WIDE tooth comb, and rebraid.
go about my day, maybe play some golf, then around 5-6pm, apply the henna to my hair, rinse out the next day around 12-1pm, so 19-20hrs later.
then DEEEP condition for 4hrs without heat with 1 banana or 1 avocado (sometimes 1/2 of each), 2 tablespoons of honey and EVOO and 1/4 cup of fresh coconut milk (blended together). rinse, moisturize, seal with unrefined Shea butter and air dry. phew!