The usage report is based on activity data for the last 30 days, excluding activities of the current day. You can narrow the time period by using the Date slicer on the Report usage page, such as to analyze only last week's data.
The usage report includes activity data up until the last complete day based on the UTC time zone. The data shown in the report is also dependent on the refresh time for the dataset. Power BI refreshes the dataset once per day.
Note that it might take up to 24 hours for new activity data to appear in the usage report.