I also write the repot date on the tag. With time I have become able to keep the watering schedule in my head. Of course if you have hundreds, that maybe less do-able (I have about 100). Flush all at end of month.
All of my plants get low levels of fertilizer at every watering, so that's another detail that can be disregarded on a daily basis.
That's what I'd prefer to do, but I gather you don't recommend it with Solo. I guess I'll need to switch to a fertilizer that I can use in low concentration at every watering. That will definitely simplify things.