Based on boiling 6.80 gallonsliters at 1.039 for 60 minutes, this will decrease your wort by 1.00 gallonsliters, bringing your after boil OG to 1.045. You wanted an OG of 1.057. It looks like it will be under.
I was worried about this one yet it came out very nice. This is not an in your face saison but very nice to sit on the back porch in the summer. Good ratings from all who have tasted.