by Joseph Diarte.
If your not switching the database you can use a copy of the current production database environment, and use your production Moodledata folder.
Once you have the current production 2.3 Moodledata folder in your new 3.3 Moodle environment point config file at the copy of the current production 2.3 moodle database. NOTE*** Not your current production environment you don't want to accidentally upgrade your production environment.
Once you have all this run the upgrade....
once your new 3.3 environment is running you will have to turn completion tacking on for each course. I would also turn the completion tracking default to yes.
Here is an article on setting completion tracking default: https://docs.moodle.org/33/en/Course_completion_settings