Neville and Luna were visiting Neville’s parents at St. Mungos when Neville spotted who appeared to be Theodore Nott lurking in the hall outside of the Mungo’s brewing lab. That had been late on the same day Hermione "awoke’, Neville reported. Andromeda’s response to Harry was the first real indication that Theo was on the run– it came shortly after the return to Hogwarts and was the catalyst to Hermione seeking help from Snape. 