This map from Agriculture and Agri-Food Canada shows the regions where growing degree days (Base 7°C) have reached sufficient levels to trigger emergence of bertha armyworm adults from pupae. Adults will start emerging in orange areas.
As adults emerge, they will start showing up in traps all across the Prairies. Keep tabs on cumulative adult counts over the next weeks as an indicator of potential risk in your area. Egg laying takes place shortly after adult emergence, and then it takes about 4-6 weeks for the larvae to mature to the most damaging instars.