The first sign for Harry happened when he was 11.
The first sign for Harry happened when he was 11, in Hagrid's hut. When Norbert was born, Harry knew instinctively she was a girl and when she started producing flames, he told her "Lykirī"
For Fleur, it happened during the first task when the idiot Ludo Bagman shouted and woke up the dragon, some flames reached her but once with Madam Pomfrey, she learned there were no burn marks.
Two Targaryen who were reincarnated.
Possibility of the two of them (and others going to Planetos