Bees not moving into foundationless upper brood chamber
I am in the process of switching my overwintered hive from foundation to foundationless. About three weeks ago, I took the bottom box off the brood chamber and put a new eight frame box on top, with six empty frames (wedge frames with wedge nailed on edge) and two frames of extracted comb from last year's super. I positioned the combs in the box as follows: EECEECEE, with the E's being the empty frames and the C's being the two combs.
Three days later, I peeked in the hive and found lots of workers in the old super comb (cleaning out leftover honey, presumably) but no drawn comb in the empty frames. A week ago, they had cleaned the old comb, but still hadn't drawn out any comb in the empty frames. At that point, thinking that the nectar flow might still be a bit light, I put a baggie feeder of 2:1 syrup on top of the frames in the top box.
I just peeked in the hive again, and found that they still haven't started drawing out comb. I am in Maine. The maples have been flowering for a little while, the dandelions just started blooming in earnest in the last day or so, and the bees are definitely bringing in pollen. It is, however, still down in the 30s at night here. But I worry that they are not yet in the upper box.
So the question is: Am I just being impatient? Should I wait a week and check again, or should I do a proper inspection now? If so, is there anything in particular that I am looking for, in addition to a general inspection?