Do I have to go in?

My schedule usually has me going in at 2pm on Monday and Tuesday, however I went in early on Monday at 3am because 2 managers in the morning asked me to come in early to help stock. Near the end of the shift, they asked me if I could come in early again the next day, so in about 7.5 hours from now, but never adjusted my schedule to reflect that I was coming in at 3am.

My question is: do I have to go in at 3am even if I said I can and they didn’t change the schedule? My schedule still says I’m coming in at 2pm.