If you are in a stand-alone home, start outside along the foundation with a real-world bug and ant killer. But only on the foundation, not on the ground! That includes any crawlspace access, basement windows and/or basement doorways. Next is all vertical section of stair steps to the house and all doorway thresholds.
Do Not Enter the House with the Bug Spray Can. Use it all on the outside!
Enter the house and go directly to the wash machine! Everything you are wearing down to the skin goes into the wash machine and set it on the longest wash cycle available with the largest tub water depth. Go directly to the bathroom and blow your nose into a tissue and then into shower - take a long and deep cleaning shower.
Follow the inside recommendations provided by Kiwi's Mom!
NOTE: Yes, it is cold in the Great White North this time of year, but ants are primarily driven by food sources. Work long and hard at eliminating any food sources.
NOTE: Water sources! The second most common reason for ants and the most common reason for other bugs! Check all pipe access points. Assure that they are closed tightly. If you have several, consider using NON-expanding insulation foam. Remember, once you are done, the can become useless! So plan your use in advance, know where you will be using it!