First, I didn’t have a christening. I had a baptism in 1977.
I was baptized a few weeks after my birth. Not exactly sure when though (all they I have a copy of my baptismal certificate somewhere in my house). My name was not a secret or surprise, and my first name was already a Saint’s name. So I didn’t need my Christian name revealed.
As FYI - technically speaking, a christening is the baby naming part. It became popular name on baptism products because some protestants don’t believe in baptizing babies, they do baby namings instead. So “christening” is a good way to make a lot of baptism gifts and cards without having to worry about people not buying them.