Yeah I struggled with going with topical or date for file naming conventions as well. I've finally settle on date because it's easier and faster for me during this entire digitizing project. But there will be time when I'm scanning or taking a picture of one of our kids projects and we don't know when it was made, really have no clue what month or year, or naming it under a topic might be better. So I still have those bumps in the road too.
But I've also experimented with tags on photos. I think you can also assign tags to none photo files as well. So we'll see how that goes.
So here's the naming conventions I've been running with.
20171111_Child's name_Artwork and if more than one on that day I'll add a letter i.e. 20171111_Child's...