2nd day of work and having to leave early, is it bad?

I will be starting a new job on Monday. I got the work schedule for that week and i finish at 6. On Tuesday i have an appointment which took me a while to make, and i would have to leave at 4. If i leave work early, will that make me look bad? It will only be my 2nd day at the job and i dont want them to think they made the wrong choice.

How do i approach this situation?

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