Convert Monthly Target to Daily Target with a twist...

What you want is 1000 hrs * ( # weekdays so far this month ) / ( # weekdays in the month ).

This is easier to calculate if you have an IsWeekday column on your date dimension table. For example,

IsWeekday = IF ( WEEKDAY ( Dim_Date[Date] ) IN { 2, 3, 4, 5, 6 }, 1, 0 )

You'll also want a column that groups the dates into months. For example,

MonthEnd = EOMONTH ( Dim_Date[Date], 0 )

Then your target might look like this (if it were a calculated column):

Target =
VAR CurrDate = Dim_Date[Date]
VAR CurrMonth = Dim_Date[MonthEnd]
VAR SubTable = FILTER ( Dim_Date, Dim_Date[MonthEnd] = CurrMonth )
RETURN
    1000
        * DIVIDE (
            SUMX ( FILTER ( SubTable, Dim_Date[Date] <= CurrDate ), Dim_Date[IsWeekday] ),
            SUMX ( SubTable, Dim_Date[IsWeekday] )
        )

I am the OP and I didn't mark the post suggested as the solution, as the solution. I did get some inspiration from the post but didn't really use it. 

Here is what worked for me - I use the date table from "Enterprise DNA" which you can read about here:

Extended Date Table Power Query M Function - Enterprise DNA

If you use the same date table, you can follow most of my formula below exactly.

Here is the measure that converts a montly target to a daily target, that only goes up on work days of the month. Note that "Monthly Hours Target'[Target Month]" is the column in the "target" table which has the target month in it (Jan, Feb, etc..). "Monthly Hours Target'[Target Hours]" is the column in the target table which has the hours in it.

I just drop this measure onto a bar chart, along with the "Target" and, each work day, the daily target will rise according to the workday of the month.