Severus Snape: New Soul

So I want Tony to be reborn as severus But the problem is when .

1 is when he is six years old

2 one month before 3ed year end

3 right after severus see Lupin transform (The Shrieking Shack happens in the fifth year which leads to Dumbledore threatening Severus with expulsion and Severus start to dive deeper into the dark arts and death eaters )

4 After lily die

till me when do you want it to happen because everyone of these would lead to a different story