Yep, that's how I do it! Antioxidants in the morning, and niacinamide at night. Have been doing that for a while, and my skin is doing really well!
Going to share this article here as well: https://www.byrdie.com/niacinamide-and-vitamin-c-4845348
Apparently it's not such a problem to combine them. I still use vit C in the AM, but my daycream contains a bit of niacinamide, so I'm mixing them anyway.