Thanks for your feedback.
I understand that it is not the recommended approach but it's time consuming to wait for every software to be installed. When you need to install 100, 300, 600 or 1000 computers on a limited time, having a reference image ready helps very much. Before the switch from HTTP to HTTPS, we used this method and it worked well.
Do you know any solution that I can apply on our case so we can do that ?
I know that some people join the domain instead of workgroup to install the softwares and then removes the computer from the domain before the capture step. I know that's not the better solution too but what is it possible to do ?
How can I authenticate the client on workgroup so he can talk with the DP on a PKI environment ?