Actually the measures in Germany started on Monday, six days ago. That's when all the schools and kindergartens closed down, many stores closed, and those interventions also triggered the first significant changes in people's behavior. Of course effectively it was a gradual change over the week, with more and more stores closing and public spaces emptying, but that Monday six days ago was clearly the major tipping point.

So I would expect to see first effects in new infection numbers over the coming week, with nearly full effect probably visible some time during the following one.