Well, I never catch the first one. After a few days I see the occasional curious worker. Depending on the winter, observations seem to have them come into the traps early on warm winters, and later on regular winters. I have yet to observe what may happen on a year with the bitter cold we experienced this last winter, and the traps are not normally what I would use.
Last year I caught about half my swarms in April, near my hives. Of course I was open feeding. I'm open feeding here at the shack, and they all seem to come in from one direction. So maybe one wild/feral colony. Other early successes involved comb with honey in the corners.
Those later traps, with just comb and lure, yielded in late May/early June. Other traps seemed to yield in the middle of summer, I wonder what may have happened in those. As of yet, I don't see any interest in the traps I placed out in the "boonies." Yet.
These traps have rendered brood comb "strings" to entice the scouts, and cotton balls with low density polyethylene bags I've kludged to hold them, from regular "A" shirt type grocery bags. The piece of LDPE is folded over a frame, held between two pieces of paper, and ironed to "fuse"them into a small bag, about the same size as a business card. No holes are punched in the plastic, it's just folded/rolled so the cotton is at the bottom, and wedged in with the entrance reducer crushing the folds to the bottom board.
The LGO percolates through the pores in the plastic. Just because you can't smell the "Lemon Pledge," doesn't mean the bees can't. My bias is the oils polymerize in the heat and age, making the lure gummy and unattractive in my estimation. I ain't a bee either. Yet.