We are consciously vague about a delivery date as we have quite a bit of development ahead of us, some of which includes research and experimentation. But it is not 2 months and it is not 12 months for sure.
The development will be done in phases with opportunities to test things as they are completed. The runtime support will be released before full editor integration for instance. We would also like to involve the community to get feedback on the user facing API (Lua and most likely in a rive.* namespace).