If I were you, I'd stay away from Salvia Divonorum!
Salvia can have a very potential for bad trips, so just please be careful when playing around with it kiddos! It's definitely not for everybody. BUT, if you are going to trip anyways, here are some links you should check out for dosing and duration:
https://www.erowid.org/plants/salvia/salvia_effects.shtml
https://www.dmt-nexus.me/forum/default.aspx?g=posts&t=17079
https://www.erowid.org/plants/salvia/salvia_dose.shtml
It's a good time :) Trip Responsibly :)