Valentine had hoped to be holding a class before now, but there had been a few hang-ups in tracking down and negotiating the purchase of a particular
vine that he plans to need beforehand. He's been assured that his supply is on the way, though.
In celebration, and to familiarize himself with the students (and conversely them with him; he has no wish to be complained at when people didn't know what to expect from a class that he, Golgotha's most renowned drug addict, would be teaching) he sends his house elf out to post signs all around the school proclaiming office hours down in his office in the dungeon.
He sets out a pot of tea and a plate of baked goods as he waits. It may be wise for visitors to avoid both.
((Reasons why it's bad to eat or drink anything left out by Valentine: he drugs food for his amusement. If anyone decides to have any, resulting behavior is up to the mun!))