To get a swarm in early spring in the mid-Atlantic region of the US east coast (DC-NYC-BOS), I would suggest mid-February feeding with trapped pollen and liquid feed, then reducing the woodenware from 3 mediums to 2, and adding a (superfluous, but it can't reduce swarming) queen excluder, and a ross round super or two.

The effect will be more pronounced with NWCs than other lines of bees.  When adding the pollen patty and feed, one must jump back quickly to avoid having one's nose broken by the colony expansion.
I am not exaggerating much at all in this description of NWCs.  They are very efficient.  I would often be splitting hives to avoid a swarm before doing my first apple pollination, a very early contract.

There is an alternate theory that merely dreaming of comb honey, or thinking about "compressing colonies" to get them up into and drawing out comb honey is enough to send the bees into the nearest tree, but I do not subscribe to this theory, as it is yet another example of "spooky action at a distance", and that's my day job, not something I want to bring home to the bees.

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