Likely an abbreviation for a specific artist or a sub-unit. In some contexts, it can refer to Jacob Akinyemi-Johnson (JAJ) , a prominent media figure and DJ, though in a "show" context with a date like this, it often refers to a performer's initials or a specific stage name.
The date format for August 19, 2018 (Year-Month-Day). JAJ - Adrian 1st show - 180819 - ptct
While there isn't a single official "JAJ" event on this exact date in mainstream news, here is the most likely breakdown of those terms based on common media archival formats: Likely an abbreviation for a specific artist or a sub-unit
This suggests the first public performance or debut appearance of a member named Adrian . a prominent media figure and DJ