This article describes how to enable the option for advanced users to calculate baselines for less than seven days period.
The proper baseline calculation requires at least seven (7) days of data to be sufficiently accurate and reliable.
To allow baseline calculation for periods smaller than seven days:
Navigate to the <drive_letter>:\ProgramData\ApexSQL\ApexSQLMonitor folder
Open the ServiceOptions.xml file with any text editor (i.e. Notepad)
Locate the <CanAlwaysCalculateBaselines>false</CanAlwaysCalculateBaselines> line and change the “false” (highlighted part) to “true”
The changed line should look like this: <CanAlwaysCalculateBaselines>true</CanAlwaysCalculateBaselines>
Save the ServiceOptions.xml file
Restart the ApexSQL Monitor service
Restart the web client
Now the baseline can be calculated for any given period that contains historical data.