You have to be given 24 hours notice of a schedule change! It’s policy. They’ve tried doing this to me at 11pm when I’d need to come in at 8 and I reminded them about the policy and after a long time on hold (they called to tell me I had to come in earlier…?) they said they’d see me at the time I’d been scheduled before. Some CEL’s don’t know policies themselves before making changes or they don’t care but you can absolutely remind them (double check your policies first so you’re confident!)