I am surprised he is not already baptized, I thought it happened normally 2-3 months after the birth. Would they announce it beforehand or at all? I'm not sure.
Well, the family has been a bit busy, don't you think, what with the pandemic, Phillip's hospitalization, death and funeral, not to mention other annoyances. I can see why it has not been done as yet.
There is also the possibility that Jack and Eugenie are waiting until they and all the rest of their respective families are vaccinated.
We've only had pre-announcements of the Cambridge kids christenings, IIRC. The rest we usually hear about afterwards, either announcements or confirmations that the christening has taken place, and who the godparents are.
I'm sure Eugenie will take to instagram and let us know all about it along with pictures. She likes to share her happiness.

It would be lovely if it could be in the Royal Chapel of All Saints where Bea's wedding took place.
When Angela Kelly wrote about making the replica of the V&A christening gown I believe she stated she enlarged it a tad, so there should be no problem with the fit.
BTW, Eugenie was born on March 23, but not baptized until December 23, during the Christmas break when everyone was at Sandringham. The christening gown would not button up the back!