When you open Copilot from the Manager, it uses the period currently selected on the screen. For performance analysis, Copilot usually extends the window to the last 30 days automatically, because a longer range gives a more reliable picture of what's happening than just today. If you want a specific range, just ask in the chat, for example: analyze the last 7 days or compare with last month. It then uses the period you specified in its answer.