It’s hard to find a clear answer to the question How long does it take for facebook username to be available after deletion? or If you can start over with a new Facebook page with your current Page username?.
When I couldn’t find a straight answer, I went ahead and changed the username of my Page and within minutes, creating a new Page with the old username. It worked. This was a couple of days ago.
I wanted to share this with others who may be looking for an answer to this question. It worked for me, maybe it will work for you.
If you are to believe some answers you find around the web, sometimes people lose usernames while attempting to transfer to a new page. So do it at your own risk.