Snape spy timeline in VW1

[Zara]

No: HPFGUIDX 175900

zgirnius:
I was a proponent of the idea that Snape spied for Dumbledore for a 
considerable amount of time, in the neighborhood of a full year, in 
VW1. For a smaple discussion, see e. g.:
http://groups.yahoo.com/group/HPforGrownups/message/166136

In recent discussions of Snape and "The Prince's Tale" I noted a 
tidbit of canon which proves to me that I was right.

First, let us recall that in Fall of the year OotP is set, Snape 
tells Umbridge he has been teaching for 14 years. That suggests he 
started teaching on Sept. 1 of the year the Potters died. Two monhts 
before 10/31, and a month after Harry's first birthday. There is 
absolutely no canon to support that he started mid-term. The previous 
Potions teacher did not die - he was alive, well, and teaching again 
in HBP. So it seems he retired, and that one would do in an orderly 
fashion, giving the school notice so a replacement could be hired.

Now, I turn to my tidbit...(emphasis mine).

> DH, "The Prince's Tale":
> he stood on a hilltop, forlorn and cold in the darkness, the wind 
whistling through the branches of a few *leafless* trees.

zgirnius:
One can argue that it can be cold and windy any time of year in the 
British Isles, (as any number of discussions of the timing of the 
prophecy demonstrate) but trees there do follow the seasons in the 
usual manner. This scene cannot be just days before the Potters died, 
because why then would Snape choose to meet DD in this nasty place 
instead of a cozy office at the school where they both work? And why 
would he fear DD might kill him, before he has said a word?

So it took place in the Fall or Winter of the previous year, months 
before Harry's first birthday in mid-summer.

Additional evidence is available in the form of Lily's letter to 
Sirius. In it she makes clear that her family is in hiding. But I do 
not believe she wrote it within a week of her death on Halloween. In 
it, she thanks Sirius for Harry's birthday present, an item she  
received a full three months previously. The letter also describes 
the party they had. I don't think she would have waited close to 
three months to write that letter.

So I conclude that they went into hiding after Snape came to 
Dumbledore. The figure of a year which I always favored, would be 
based on Sirius's angry accusation of Peter in PoA. During this time 
DD grew to suspect a spy in the Order, as someone was reporting on 
the Potters' movements, and Dumbledore got to see just how seriously 
Snape meant that "Anything".

A far better reason for him to eventually decide he could hire Snape 
despite his DE past than just that Snape showed up one day and said 
he was sorry.