As soon as we have used our username (shared with audience) we are forced, in order to be sure nobody can see what we are preparing next, to generate a new name because some user may randomly try to connect again and, with some luck access questions when we are doing some test…

Would it be possible, as soon as you start to pay, to give a bit of freedom in the username selection? Maybe, for basic account (like the one I use) forcing one word but give freedom on number?

Another way could be to add an option who only allow mobile phone from my account to connect? It will be a kind of debug mode who, when activated, will only let my account to connect and to see questions for testing purpose.

A third way could be to create for each account a private user name and give account owner the possibility to switch between public (when presenting) and private (when preparing and testing).