Insulate the new building before the windows are installed?

Hello! Is it possible to carry out the roof structure insulation or insulation between rafters in a new building before installing the windows? Reason: Unfortunately, the installation of our windows is delayed by 8 weeks. To avoid being completely inactive, we would like to start the insulation in June/July. Thank you very much!

Of course, there is no objection. However, the best option would be roof insulation after drying the screed. But it is not a must, just ventilate well.

We have already installed the insulation, as it is extremely difficult to do so afterwards with a hip roof. So we installed the insulation before closing the roof truss. The windows will only be installed in a month...