The call to go home for level specific school quests is still an issue. I just got to level 24 and Ambrose is telling me to see him when there is no reason for me to go home until I am level 26. Also, after I had completed the 48 school quest (because I knew to get that pet and last spell quest), I got a notice to see my prof when I ported home. This area of the program still needs work. The last group I quested through had a serious lack of "call home" notices, but I am trusting you are working on that now. The biggest problems appear to be occuring in Krok, where Ambrose is getting a bit too lonely for his own good and calling students home for nothing.
There are standard times to go home for in and out of school spells (levels 1, 5, 8, 10, 16, 22, 26, 33 and 42), then for the school related quest you have those levels usually ending in an 8 like 28, 38 and 48 (I can't remember the earlier school quest levels). This is not a spoiler, this is what the game should remind you of with that "call home" feature that needs just a little more tweaking.