Your mileage may vary, but this homemade ant trap literally worked that quickly for us. I mixed it up in the evening after ants had ruined my dinner plans (what kind of ants eat almonds, anyway?), and saw all of two the next day, both in the trap.
In a pint jar, add 1 tsp. Borax, 6 T sugar, and fill to the top with hot tap water. Shake until everything is dissolved, then fold or crumple up a paper towel in the solution, place it in a shallow dish (e.g., a tupperware lid) and place it along a major ant thoroughfare.
This cost us basically nothing, was more effective than most purchased ant traps I've encountered, and since one of the recommended uses for Borax is scrubbing stubborn dishes, I didn't even have to permanently sacrifice the dish!