Actually, if you read my next sentence, you'll see that I said that I hoped the school would be able to give more than a week's notice for the actual appointment times. At our school, kindergarten registration is in February. School starts in August. Tell the parents in February that assessments will be happening on August 25-27 in the afternoon. They might not receive their actual appointment time until July, but at least they'll be aware that they'll be receiving one. (But I also think the school should be able to assign the appointment times farther than 1 week in advance!)
If I knew that my child would be needed on one of three afternoons, I would do my best to make sure that I didn't schedule any critical meetings, business trips, etc for those days until I knew which day my appointment was on, or that I had a "back-up plan" in place for those afternoons. It's not unreasonable to ask parents to bring their children in for an assessment. It is unreasonable to give them a week's notice and assign a time without consulting them.
I will also bet that in some information sent home from the school or posted on the school website that there was information long ago about these assessments.

I'm gonna bake you some cookies!
However, I did have one issue and posted about it and kind of got jumped on by teachers and I guess that did not put a really good taste in my mouth. But that does not mean I hate, disrepect or have issues with teachers in general.
Just know that for part of that time I am working on lesson plans and trying to make my classroom a great learning environment.
