I guess it depends how did you submitted your documents, Did you use IRCC web form/via GCkey account/ or post?
If you used IRCC web form the you will hear back from them roughly after 15 to 20 days. When you use web form, it says that response back is 10 days. I have used web form twice and each time I had response after 20 days.
Thanks so mush for your quick response. I actually sent it via web form and also through enquiry contact. The VO is London and was sent on the 18.09.2018.