I have always found that the absolute best time to get good comb drawn was in
the middel of a strong nectar flow.  While one can get some comb drawn by
heavy feeding in the absence of a nectar flow, the result has almost never
struck me as worth the effort (you get a lot of cross comb).  Accordingly, I
always get my new frames drawn out during a nectar flow.   True, you will
lose some potential crop, but you gan the drawn comb for future use.
 
W. G. Miller
Gaithersburg, MD