The 737 offers two different alternate forward CG settings for greater performance margin or more thrust reduction.
As long as we did our w&b ourselfs on our EFBs and the w&b program directly interfaced into the take off performance and the correct alternate forward CG option was automatically chosen. Now that we get ACARS loadsheets we usually don't bother with it as the difference in performance is rather small, but in a real limiting situation i would check what difference it makes. On our 700s option 1 is at or above 15% MAC and option 2 at or above 20% available, on the 800s it is 20% and 25%.