Bleaching my hair into two sessions? Bad idea or safe?

Most likely a very bad idea unless you have very light hair already and even then, you will also need a lilac toner to remove brassiness. Store bought box kits are not strong enough, you will always be left with orange hair as red is the hardest colour to lift. This is really hard even for professional hairdressers. (I used to be one) Doing it in two stages is also a bad idea. Even with a timer, you will end up with banding, the colour difference where the edges meet. The only time I would ever say you might get away with it, is for pre-bleaching because you want to colour your hair a vibrant red.

smart idea. is it specifically on the scalp bleach? if its not you cant get it on your skin

it won't turn out the way you want it to doing it from home. it won't get an even bleach. it won't be strong enough, it will turn out orange first. even professionals usually require more than one session for a whole head bleaching. if you try it at home you will end up frying the sh&t out of your hair & still won't get it as light as you want it. sorry but try to go to someone get it done. or order some professional grade hair kits.

What color is your natural hair. I would only go one shade lighter. Anything else and I'd get professional help.

What color is you hair now

I wouldn’t do it. Do you really want to fry your hair? Once you have you can’t save it, you have to cut it off.