My CO said that they are proceeding with the background verification. I did not understand whether they started it? or they are in the middle of it?
There's no way to tell from this wording, nor how long it will take in total. And you can't tell from what happened to someone else's case, either. INZ contact every employer and every educational establishment, to ask them to verify the evidence you have given, and they have to wait until each one replies. As you can see, the amount of evidence can be different for every case, and how quickly (or not) each person replies can also vary.