I've been feeding syrup to minihives for a couple of weeks now, plus a few of the larger polys too. If the fields hadn't been so wet I'd have been feeding a few more. Bees are in the feeders taking it well.
In my experience, for a Buckfast type bee at least, a good healthy colony will not fill up laying space they need for brooding. In milder temperatures they are burning up stores quickly enough that it's not even an issue, when colder they take the syrup much slower. Different story for a struggling colony that might well be clogged up, but even then it's usually as a result of the autumn feed not spring - they don't seem to feed if duffers.