If i want to bleach black hair, how long until i can dye it brown?

I have blonde hair on the top, and black on the bottom. If I want to bleach the black hair on the bottom (I know it will turn orange) how long do I have to wait before I can dye it a light brown?? Help!!

well do u want it blonde,black.or light brown?
if u want u could dye it all black!
or u can dye the black blonde so it will match the top of your head!
or just dye the whole thing light brown!
and dont bleach out your black so it will turn orange!!
who wants orange hair???

the rule is to wait 2 weeks.. but u can do it right afterwards if your hairs healthy. make sure that you pick a haircolor that says ash or neutral brown (dont buy one that says warm or golden) because the ash will get that brassy orange out...