M.G.
If your test is abnormal, I don't think them waiting a week (2 or 3 more days) to let you know would make a difference. You have no reason to believe your results will be abnormal, so stop worrying over nothing.
However, I have a story to share with you. Since this is your 2nd mammogram, I am assuming you are 41, which means your results can come back saying "normal, but you have dense breast tissue." That is what happened to me (I am 42). My doctor said it is very normal to have dense breast tissue in your 40's, and not to worry. I did research and learned that dense breast tissue shows up white, and so does a tumor, so how do you see white on white? You don't! I was upset that my result came back as "normal," when, in my opinion, it should have said, "inconclusive - further testing is needed." So I demanded further testing and had a breast MRI. Glad I did, b/c something came back as "abnormal" (they said it could be nothing, but something is on my left breast that they want to check out). So I have an appointment for an ultrasound next week. Good luck!