Tom's father does not give him much trouble, really, about the vacation, and he thinks the man is just happy to get his unnatural son out of his house.
He is lucky, he supposes that he gets no worse than a bruised cheek from Tom Riddle Sr.'s anger – and even luckier that his mother is still confined to her room, so she is not in the way of her husband's wrath. It is why he chose now to tell, instead of waiting until the day of departure – by then, his mother might have been a target again.
He still has a fortnight to waste before the trip with the Lestranges, though, and it is not as if he has anything better to do with the time – sneaking out into the city still holds a great appeal, even if they are all filthy Muggles.
He cannot use magic outside of school, or at least, none that can be traced back to him. Once out in the streets, how are they to know such spells originated from the wand of poor, innocent twelve-year-old Tom Riddle?
And so he waits, and so he amuses himself, and if some little waif girls do not make it home to their mothers unscathed, then, who is there to blame?
And so he waits.