NEWBIE HERE !How long to leave henna on first time?

Just did my strand test & got jet black. Gonna go for it for first time this weekend. How long to leave henna on first time? My hair's mostly black with scattered gray. I have Ancient sunrise for AFRICAN HAIR BLACK. Instructions say several hours. Is that 2,3 4 hours? How long for indigo? It says one hour.Is longer than that bad? Is there a time limit for both?

For the henna step, I would go 3 hours your first time. Two hours is the minimum I've found works well in a 2-step process because you need a good solid foundation of henna in your hair to get the indigo to stay in your hair well. Leavinghenna on longer is not a problem. Some ladies sleep in it overnight just for convenience' sake.

For indigo, I leave it on for 1 hour for black. Leaving indigo on your hair a lot longer, say 2-3 hours, wouldn't be great since it could be pretty drying. It doesn't condition hair the way henna does. 1-1/2 hours would be okay, but I wouldn't really go longer with indigo.

Tomorrow...or Sunday..is thebig day. Do I have to totally dry my hair after shampooing it before applying henna?  Do I have to dry it before applying indigo? I heard somewhere that damp hair is good because it would absorb the henna dye better thru capillary action the way a squeezed out  damp sponge will soak up water better than a totally dry one. Also, I think I heard...or maybe you told me....that I not put conditioner inmy hair for 24 hours after the henna & indigo so the color can set.

Damp hair is best. No conditioner between the henna and indigo. Afterwards is fine, once its in your hair its not going any where. Unless you use a detergent based soap (dish soap or a clarifying shampoo) - this will remove some of the indigo, but not the henna. The henna isnt going any where, ever.

So...

henna step: shampoo only. Be sure to wash and rinse well.

Indigo step: Shampoo with your normal shampoo, unless it is a clarifying shampoo then grab something more gentle (cheap VO5 works). Wash well, conditioner if you want.