Courses begin 15 minutes after the time indicated, colloquially known as the "academic quarter", and end 15 minutes before the time indicated.
In exceptional cases you will find the indication "s.t.". (sin tempore, translated: "without time"). These events take place punctually at the time indicated.
The times are often indicated with the Latin additions "c.t.". (cum tempore, translated: "with time"). For the sake of clarity, however, this information is not given in everyday university life.