Baylor center of garland?

i'm supposed to get an MRI at the baylor medical center of garland in garland, texas. my doctor told me they'd call me (she told me on monday). is there a certain part of the week they call? cause i need to hurry up and schedule it so i can let my boss know when i'll need off. it's wednesday right now. am i supposed to wait a few more days or do i just call them?