Mine is frizzy too. I cant use permanent coz they just wash out.

Testing the time, Cut an inconsipcous bit out, and apply a bit of dye to it, checking it every 10 minutes. sometimes hair is healthier during pg and sometimes it is more damaged, depending on the person, but there is more of it, so it will be different to pre pg.

Also dont forget the sensitivity test. you dont want an allergic reaction.

A Semi is safe during pg because it is not absobed into the blood stream, and uses lower strength developer. Make sure the room is well ventilated though so you dont breathe in the fumes.