Re oxidising

You should be, but there's an easy way to check if you want to make sure, or for future reference. just take some straight peroxide, like 20 vol, and apply some to a test strand. If it darkens, you'll need to rinse more, if it stays light, you're good to go 🙂 Ideally though it is best to wait a month from your last dye/bleach though to prevent more damage, and to let some oils build up in your hair first or at least slather it with coconut oil a couple hours beforehand

Are you talking about doing a blonde box dye on your already blonde hair? or using it over the part that is reddish? If over the reddish part, I would definitely use another color remover first on it if it was bleach blonde before - there's still a lot of dye in it it looks like. Usually I get the best results/no reoxidizing by rinsing for a half hour, drying it completely, then rinsing for another half hour.

If you're talking about using a blonde dye over the blonde I definitely wouldn't, I would try toning it with a violet semi heavily diluted in conditioner first, and if it doesn't look cool/light enough, I wouldn't do anything more than a 10 vol bleach on it or a a20 vol bleach bath

I'm going to have the dark bits pre lightened with bleach and then a ash blonde all over , I have used 3 boxes of b4 and think I'm at my lift limit ,

I just want peroxide to touch and my hair to lighten but I will do the strand test thank you