coloring already colored hair

i went to the salon a few times to highlight my hair, but i just can't keep up w/going back every month (and besides, it's expensive!). i've decided to go through w/highlighting my hair at home. i didn't get the color strands from feria cuz they didn't have any, so i'm just gonna take a brush and work with regular feria. ok, here's the problem. i got color 55 (bright auburn brown) for my BLACK hair w/brownish-orangeish highlights. i did a test & it worked wonderfully on my colored sections (they turned out bright auburn) but did absolutely nothing to my black hair. on the feria website, it said that dark hair shouldn't go that high on the color scale, but o well. it also said that to get a vibrant color, u should use the color bleach blond before applying the color. should i use feria's bleach blond? will it work? also, how long should i wait to color my hair after bleaching? thx for any suggestions!