So if I understand it correctly, you're going to be incrementally adding new pages on the ww2 subdomain while content still exists on the www subdomain. This will be done slowly until all of the www content can be 301 redirected to ww2?
If that's the case, there's a few other things that could be helpful to know:
- What's the expected timeline to get all of the new ww2 pages live?
- How similar will the ww2 content be to the www content?
- Is the TLD staying the same and only the subdomain changing?
Ideally, everything would be added to the production site and redirected all at once.
However, if that isn't an option I'd probably try to implement the redirects from www to ww2 incrementally as well. Otherwise, Google will be able to crawl/index content from both the www and ww2 subdomains, leading to duplicate content issues. I'd try to keep the website architecture fairly consistent between the two so preserve the UX/equity signals between the two subdomains.
It's tough to give insights without more information, so I'd be happy to chat more about this!