Job Question

Well I'm planning on being a vet and I was looking for a job so I just applied everywhere. I applied at Home Depot and multiple vet clinics. One of the vet clinics I'm pretty sure will call me back this week for a job but Home Depot called and I have an interview for tomorrow. I'm only working part time because I am a full time student. So if I get a job at the vet place I won't want to work at Home Depot. My question is if I get both jobs how should I tell Home Depot I don't want to work there because I got a job that goes with my career? I have to have 250 hours working with a vet to get into my vet program... I just don't want to waste their time with the interview and paperwork if I get the job at the vet place. Thank you!