“MGM announced last summer that it would open Bond 25 on Nov. 8, 2019, but it’s unlikely to do so.”

That’s according to Variety in an article reporting the release date of Danny Boyle’s unnamed project for Working Title scripted by Richard Curtis.
Source: Variety
While Variety gives no indications as to why the proposed release date could slip, MGM still has no distribution partner/co-financer. You should follow The Spy Command for why that is important.
Adding some weight to Variety’s assertion is the response of James Bond Live (run by MI6 HQ) to a comment by The Spy Command on Twitter:
Variety is just reporting what we’ve been given a heads up to over the past few weeks. A lot of nervousness over the date being pushed.
— James Bond (@jamesbondlive) April 17, 2018
If that November 2019 release date is to be met then shooting should commence in just seven or eight months. However there appears to be a distinct lack of progress compared with the other recent Bond films at this stage and so it is looking increasingly like 2020 is more likely.