It won't be more than a tech preview until after Go is stable on the M1 which is likely to be January/ February. Once that happens, it should be pretty quick.
This certainly works for Home-brew apps. I think Docker is a bit of a different cookie though. Talking to a VM over the Virtualization Framework likely requires being a little more native.
Adobe and Microsoft took months/years after Apple's PowerPC and Intel transitions... complex software is complex, it's not like they get the new machines, flip a few toggles, and hit compile.
Source? The developer machines Apple shipped out didn't have virtualization support so they couldn't start on that until after the M1 and I haven't seen anything that says Docker got M1's early.