A wizard is a special plugin for the world builder. For more information’s about plugins in general, please look into the section here.
There are two ways to run a wizard.
1st, when a project is loaded. The Builder Project Settings has a section for WizardsToRunAtOpen. This can be edited and all wizards will be run in the order they are listed here when a project is loaded. If you want to run a wizard only once, you need to remove the name of your wizard from this list.
2nd, when a wizard is started via the wizards menu. If you enable a wizard to be listed in the wizard menu, the user can start the wizard whenever they want.