Well, they started in March. It is now September. It's going far too slowly, and all because of 'waiting on steel'. It's doing my head in. But here is where we are. I just hope they get the roof on soon ... winter is around the corner.
I feel your pain. It took 5 months to build our kitchen extension. We too had to wait for a steel beam, as well as digging deeper foundations. It's worth it in the end, although this looks a bigger project than ours, so may take longer yet. Good luck!