We often put together dashboards that show performance for the current month against goals.  This requires that we determine the percentage of the month already passed in order to build the forecast for the remainder of the month.  Here is a formula for Google Sheets that allows you to determine the percentage of the month already passed as of yesterday (i.e. the number of days of the month already passed/the total days of the month).

=(day(now())-1)/DAY(EOMONTH(now(),0))

Now you can divide your actuals by this percentage to determine the forecast for the month.