All depends on what you call inaugural flights.
For me the only inaugurals are the very first commercial flights of a totally new / revolutionary aircraft type.
My first inaugural flight was the first commercial flight of a Concorde with Air France from CDG
to Rio de Janeiro on board F-BVFA Jan. 21, 1976. It's been 37 years already. I was not on any forums as there was no Internet back then.
My second inaugural came way much later with the very first A380 commercial flight with Singapore Airlines Singapore Sydney Singapore 25/26 October 2007 with my birthday on board. Aircraft was 9V
My third inaugral flight was the first commercial flight of the Boeing 787-8 Dreamliner with ANA from Haneda to Frankfurt, 21 January 2012. Aircraft was JA
My fourth inaugural flight was the first commercial flight of the Boeing 747-8i (well let's say a/c one is not really a new type rather an extended version of the 400 series) from FRA
, June 1 2012. Aircraft was D-ABYA
So that makes 4 true first inaugurals to which I can add other Singapore Airlines A380 first flights to Oceania/Asia/Europe
London Heathrow LHR
Tokyo Narita NRT
Hong Kong HKG
Also the first A380 commercial flight CDG
crew training flight / short haul with Air France 12 June 2010. Can't remember the aircraft name. There is a trip report I did on this forum. You can look for it. It has all the pictures and information.