Not an excited daddy

We’re 5 weeks 2 days pregnant and have already decided on our boys name, but whenever I bring up the topic of a girls name or even mention the baby such as “oh, today it’s the size of a black peppercorn” he gets annoyed because it’s “ 7 1/2 months away,” and why am I “worrying about it all now” but I can’t help it? It’s my first baby and I’m just super excited and he doesn’t seem to be feeling the same..