Hello Thanos,
The desciption of the Low PEG Ratio portfolio states:
The Low PEG Ratio portfolio follows a disciplined approach, selecting Canadian stocks with a low PEG ratio every mid-month.
So, to make it clear, this portfolio is updated every month, and the chosen date to do so is the 15th or the following open day if the stock market is closed on this particular day.
There are no big reason why the 15th has been chosen other than we had other monthly updated portfolios that are re-assesed on the first day of the month and we wanted to pick another date for the Low PEG Ratio.