You can also hit Ctrl + on your computer until one petal is the size you think it should be on your screen. Put a piece of paper on your screen and trace with a felt tip marker. This pattern really doesn't have to be exact so you can do it easily.
I'd cut all my petals pretty much the same and just overlap them until I have the flower looking like I want it to look.
There are several methods you can use to turn under the edge. Do whatever is comfortable for you. I'm sure the gift will be loved.