While Alex was at university, Diana and Hee-Young had begun making the adjustments that Alex had suggested to their companies. It wasn't that they had gone out of their way to verify whether or not such plans were actually viable. But rather, they trusted Alex to do what was best. Even if they deep down expected to lose money over the whole ordeal.
Of course, money wasn't generated overnight, and it would take time for these changes to properly take effect. Thus, all Diana and Hee-Young could really do was sigh and roll the dice, waiting for either a return on their investment, or to suffer losses.
In the meantime, Diana decided to introduce Alex to the members of the board, and the top executives at the company she was now the majority shareholder of. Thus, Diana had set a time and date for Alex to visit the corporate headquarters of his mother's company. Which just so happened to be on one of the days he had off from classes.