The phrase "debut appearance" refers to the very first public appearance or performance of someone or something, typically in a specific event or venue. Full definition
This weekend saw an inordinate number of debut appearances in the Premier League thanks to the international break last week. (caughtoffside.com)
The stylish 4C will make its SBK debut appearance at Silverstone this weekend. (ausmotive.com)
Having heard rumblings about Crash's debut appearance on a Nintendo title I had kept my guard up until I saw his spiky hair on my laptop screen in the flesh. (musingsofamariominion.com)