Alesia, GIAB should be able to heal all layers, the dermis, epidermis and stratum corneum at once not just the first layer if you keep it on long enough. I said it takes about 4 days to heal the dermis and a little longer for the remaining 2 layers.
There's also no guarantee that this product will work for you, so don't get your hopes up too high though but I'm hoping it does. You'll be able to tell by the next morning when you wake up and look inside the mirror if you notice new and improved skin.