Most the pest control companies explain that when they apply the treatment, the ants often become more active and more visible for a time.

It's particularly helpful if you can locate the main nest, one that's somewhere in the garden, landscape or wooded area. The problem is that the best time of year to do that is April through October (at least in our region) when they actively trail between the house and their main nest.

Carpenter ants are a symptom of a problem, not the proplem. Look around and determine why they are where they are and fix that and the ants will simply leave. Carpenter ants in your house (that would be the only reason for "controlling" them) that is an indication that there could be a problem with the house structure, a leak producing wet wood which carpenter ants like and seek out and find.
Simply putting down some poison to kill them, and not fixing the reason they are there, is not a good solution.