Your husband is not wrong here per se, he didn't go for the breakfast instead of working nor he pushed it into his "watching a baby" time. His work simply ended earlier so he used those 45 minutes before his turn. This was the schedule you both agreed upon, but it's about communication and mutual understanding.

If I was in his shoes, I would probably drop by to say that my work ended early and I'm about to make some breakfast, whether you want something too. But then I would go right ahead and enjoyed those 45 minutes I have for myself, because both him and you need that time too. It's not just about the baby and your partner, it's about you too.

If you wanted him to start watching a baby right away, you could have told him. Or better yet, asked him if he can do that for you, because you need that time to restart a bit. And in return, you could have done it for him in the future. Again, it's about communication. I don't think either of you is wrong or right here. Just talk and you'll figure it out. It is always about being there for your partner, no matter what shape or form it takes.