The char bar looks nice visually, but what you really need to know is how far behind/ahead you are in your hours totally.
If i understood correctly, you are interested only in your current saldo and your current deadline, so you could display that information in 2 seperate fields (e.g. below the chart). Of course, you could also mark the deadline with some horizontal line in the graph.
How about a pie chart where the total size represents the minimum goal and add pie slices for each day with actual days that met the minimum one color, days with extra time another and then fill the remaining days as gray slices with the number of hours the employee would have to work divided evenly among them?
A line plot with "working days elapsed" on the X axis and "fraction of monthly required work done" on the Y axis? With only a few data points, it should be clear by visually extrapolating whether you'll hit the top early or late. The plot would look like an irregular staircase.
ps. "The Visual Display of Quantative Information" by Edward Tufte is a great book for ideas on this kind of topic.
To take Dickon Reed's idea one step further, why not do each point as a +/- hours ahead or behind, with your baseline always 0. That way you have more detail. I'm not sure if I got my point across, but it's hard to do without an example, and I'm short on time.