Q:

How long should I wait before adding content to a 'moved' website?

I 'moved' my website from domain A to domain B. Did all the necessary things (301, notified Google in Webmaster Tools).
The question is, how long should I wait until I can put new content on domain A?

A:

You can use the domain A right now if you want.
The only issue you can think about is URLs which already existed on your old site on domain A because users could be redirected to the domain B. Make sure you don't have duplicated URLs between your new site and the old one on the domain A.

