:alarm_clock: Toggl tally is a rich Python command line tool to track hours worked towards monthly targets and forecast hours per day with Toggl Track.
If the invoice date last month fell on a non working day, then the last invoice date occurred before it and was inclusive. Under the current logic, the hours for the last invoice date get double-counted, as the first billable date of the current month is assumed to be equal to the last invoice date.