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

Hello

Before I continue, please do not tell me to go to a professional because i just can’t.
This is my first time bleaching my hair by myself and to be safe I wanted to bleach the bottom half of my hair (with a timer of course) and then finish bleaching the top a few days later (with the same timer I recorded previously) Is this a bad idea? I have long and thick hair so I’m just nervous about doing it all in one shot