Steven Zahm@ carolin
re: if I use the Connections panel for example, to unlicense the sandbox, and add the live site URL
What do you mean by “Connections panel“? Do you mean your purchase history page where you can manage sites or the Connections : Settings admin page under the Licenses tab?
If it is the former, the site activation/deactivation does not “migrate” from manage sites to the actual site. You still need to activate the license on the actual site.
My recommendation is to deactivate the license on the sandbox site on the Connections : Settings admin page under the Licenses tab and then activate it on the live site. The do the reverse to go from live to sandbox.
re: is there sort of a ‘rule of thumb’ of how long it will take for the switched site to be able to recognize the activation of the license and be able to be updated?
Immediately. The license status message on the Connections : Settings admin page under the Licenses tab are/were deceiving. They were cached for a 24 hour period so may not have actually reflected the actual state until that cached message expired and then refreshed. The latest version of Connections has corrected, I hope. So the status messages should be more realtime. They are still cached for a day, but more actions force the cache to expire and therefore it should be refreshed. I really hope that make sense!
Hope I have answered your questions!