cub, if it were me i would let them store some syrup in the comb, but be careful not to let them store so much that the broodnest becomes 'honeybound'.

you still should have some fall forage, and i would consider allowing them to store as much of that as possible and then supplement with syrup if needed to bring up to winter weight.

generally speaking, about 2/3 of the hive cavity should contain stores by the time the first frost hits.