There are a number of providers that do schedule their simulator sessions in the evenings and at weekends. We also do this.
I would imagine that the ground school would have to be completed during the daytime due to its length, but along with us, most schools will run their sorties in the evening period if necessary. The course duration however would probably still be 8 days straight. So if you are choosing evenings to fit around work, you might find yourself a little tired!
The best way is to actually have a week off to complete the course, so you have consistency, this way you will learn a lot more - or at least it will sink in better.