URGENT! Hair dye

[DaisyChaining]

My hair was a horrible bleach blonde job, with a few brassy tones and pretty bad roots - after I went to the hairdressers and ask for a balayage and paid £100 for the privilege 🙄

I can't afford to go back to the hairdressers, so I've just put a plum semi permanent dye on it. If I leave it for longer than it says on the box, will it go darker? The comparison pictures on the box are all with brown hair. Mine's lightish blonde. I don't want bright purple hair, especially with job interviews lined up (though honestly, my hair looked so scruffy before it probably would still be better🙈)

It's been on for 10 minutes so far. Box says 20. I'm thinking 30? Or longer? Any advice?

Have you put it on all over? Id maybe have done the darker hair 10/15 minutes before putting they dye over the light/blonde hair to try to even it out as it will take quicker in the blonde hair.
I'm no hairdresser but from loads past experience that's what I've done.
Hope it turns out ok!
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Sorry for the typos!

Thank you! I probably should have done that but won't it be very much brighter on the blonde? What I mean is, if I increase the time, will it go darker on the blonde bits? Or just brighter 😨

From experience plum (with red tones) will not stick on bleached hair. But my experience was with permanent, I know semi-works differently. I'd leave it on for longer but after a certain point your hair will stop going darker so don't bother doing longer than 30mins.

Oh nooo! I did see on google it was better to use semi permanent than permanent to go this colour when previously blonde. 8 minutes to go till it's been 30 🤞🏽

Yes it probably is because the red tones in permanent won't stick on bleached hair. Worse to the worse, if it comes out rubbish, you can always do lots of shampoos and stick a brown dye over it. Red/plum is stunning but it wouldn't stick in my hair after a few days because my hair had too much bleach from previous highlights.

It looks lovely hopefully it sticks. thank you for your help