There is somewhat of a risk if you start feeding too early, in that the hive will be stimulated to produce more brood than they can keep warm. If there is a sudden freeze, the uncovered brood will get chilled. The bees will then have to clean out the larvae from the cells and start all over again. The results - a sudden weakening of the hive, but they usually recover alright. You'll find all of the chilled brood in front of the hive. As to the question, it was in the 50's here in MA and the bees are presently bringing in bright yellow pollen so their feeding will start because the weather for the next 7 days will also be moderate. OMTCW