Casi, you can just use the size that is on the pattern for the pocket size.
I have made a few of these and you can alter all the sizes. I ended up getting rid of my bowtuck patterns because I don't even use them anymore(so I can't help you with original sizes). That's what I do for the bags I make now. I kept altering the pattern and came up with one of my own. I've also made mine without the pocket in the front, but I quilt all my fabric before hand on the longarm for more decoration.