Did I miss the the nectar flow?

:scratch: My package hives have really slowed down on building comb. I got two packages the first week of April and two packages the last week of April. The first two are working their second and third mediums for brood. The last two have barely built comb on 5-6 frames in one medium. The last two are still being fed sugar water. I've noticed that some of the first two are taking sugar water out of the humming bird feeder. Should I slap some sugar back on the first two? What could I do for the last two to get them drawing more comb? My desire was to have drawn comb and stores with each hive having 3 mediums going into winter. Too early to panic? If they don't meet the target, when should I combine hives? Eggs/larva/capped brood present in all the hives. All appear to have eaten what little stores they had a few weeks ago.