Following the #AppleEvent announcement yesterday, I saw many comments about a possible schedule of events this fall. Many of them are putting the release of the Apple Silicon Mac in October.
There is no way this is going to happen that early. macOS Big Sur is still at Beta 3. Developers are hard at work adding support for widgets and other iOS 14 stuff. I would expect iOS 14 to be released at the end of September. iOS 14.1 will come out in beta at the beginning of October in order to support the new iPhone shipping later in October.
Now back to the Mac. I expect Big Sur to be released at the very end of October if not November. The actual Apple Silicon Mac will probably be announced at a different moment than the iPhone. Apple doesn’t like to mixed up things in their keynote. The actual shipping date could be at the very end of the year, just in time to catch the ramp up of the A14X production rumored to be starting in Q4.
In summary: Apple Silicon Mac to be released late in 2020.