Can't Leave Town

Hello there. I have a question concerning the beginning of my game. I want to set an event so that you can't leave town until you visit the professor's lab and go through those events. Not because of having a pokemon (you start the game with a pokemon).

There is an example of this in the outdoor "Test Map" that comes with Essentials. They are the three events lined vertically below the northern water patch.

The only difference in your case is that, rather than the events' second pages depending on Global Switch 2: Got Pokemon, they should instead depend on a different Switch which you only set once your business with the Professor is done.