How long should i wait in between bleaching?

-ok so, about three weeks ago, i went to sallys and got 30 vol , bleach . I bleached my hair but i was nervous about damage so i washed it out after about 40 minutes.... it came out a light blonde but not that light, but i dyed it hot pink any ways.... it came out sort of a pinkish redish purple... but it was all sort of uneven....it looks really good... but i would rather have it all an even shade of hot pink...so i was thinking, when i have to bleach my roots all over again (which would probably be in about to or three weeks,) i wanna just bleach it all over so i could even the color out. but I don't want my hair to fall out from bleaching it or anything... i take very good care of my hair, condition it every time i shower and its very soft...and i would say its just as healthy as ever. but i just don't no what to do... so basicly my question is, should i stick to just bleaching just my roots. or do you think it would be ok , if i bleached my whole head again ? the time in between bleaching wuld be about 5 or 6 weeks