When was Dawn formed?

[Buffy Summers]

It has that feeling because we didn't at that time know who she was talking to, who Dawn was.

 

[nerd4hire]

It's the same writer's trick you see in the Angel episode Just Rewards. Spike comes to Angel's bedroom late at night and the conversation winds up here.

SPIKE
I can't live like this, Angel. Being useless.
(sighs)
Being nothing. I want it to end.

We think Spike is wanting to die, and he's offering to martyr himself in Angel's cause, but no, as it turns out he isn't saying he wants it to end, so much as he's saying he wants to stop being usesless.

 

[The Arcane]

There is actually a scene in Buffy vs Dracula that pretty much guarantees that Dawn was only created in the late moments of that episode.

Buffy: Thanks, Mom. Everything was yummy.
Joyce: Hey, you up for dessert? We could, uh, take a drive, get some ice cream.
Buffy: (stands) You know, I, I would, but I kinda have to get out on patrol.
Joyce: Now? It's 8:30.
Buffy: Well, vamps don't really care what time it is. You know, dark equals dinner bell.
Joyce: Right, of course. (Look around empty table) You know, I'm gonna have to get used to this place without you again. It gets so quiet.
Buffy: You know, maybe we should make a regular date of this, when school starts.
Joyce: (nods) Mm.
Buffy: I'm sorry. Duty calls. It's a total drag.

Now granted you could just assume that Dawn was out or up in her room but the mood of the scene and Joyce's words make it pretty clear that she is living on her own at that point.

Besides, can you imagine the house being quiet if Dawn really was living there already? 😉

 

[Your Creamy Coolness]

I always took it, as she was actually made the few moments before Buffy said "I'm going out" cuz theres no mention of her up until then?

I agree. I figured Dawn was formed and the spell was finished just as Buffy is leaving in Buffy Vs Dracula!

 

[Chasing Cordy]

like it's been said MANY times before, we don't know if they were Faith's dreams or buffy's so we don't actually know where those warnings came from.

I wonder why Faith would get dreams about something so tightly connected to Buffy?
This tells me that the dreams must be Buffy's

 

[Edmund Blackadder]

I wonder why Faith would get dreams about something so tightly connected to Buffy?
This tells me that the dreams must be Buffy's

Thats not an assumption that can be easily made.

Dawn is made from Buffy's blood, but within that blood lay the Slayer essence. When you factor that in, you could argue that Dawn is also linked to the line(though not as a Slayer) which means she could be connected to all Slayers, including Faith.

This was something I expected after Blood Ties, yet it never really got mentioned then in Potential it was hinted at but nothing. Still, you never know with the future how this works.