I think the issue with BG check changing is that sometimes its right before DM, I've even heard of it changing the same day as DM, so its hard to tell.
Also, I think the processing times are somewhat linked to your Province as well. Like I know Alberta you wait sometimes a year or 2 years for the nomination, so not sure if that means its prioritized when you send your application to CIC. Whereas the other provinces the nomination seems to be a lot quicker. But I think in general it is linked to the province also, not just your application date..
I think some applicants from the start of November are just starting to receive DM etc.. So its going to be soon for us, but just a waiting game now..