Anywhere from a couple hours to a couple days. Depends on how close the release is to the current stuff and how much time eqMule and others have to figure it out.
Considering how up to date eqmule has been with the beta compile, I would assume not terribly long barring his real life schedule and Fry and htw's work schedules.
We always do everything possible to get a release out as fast as we can even if it means lack of sleep for days on end. We don't know the full extent of what is going to happen. There could will be emergency patch after patch which wreaks everything.
How long is a piece of string? We don't know, but we will do our best for fast update. We have been planning for it for quite awhile.
I'm going for the record with this one 1 hour and 58 mins...
No but seriously plan for 8pm est. that's the time I have released core the last 12 months and I don't think it will change today.
If it happens before that it's either because I got thousands of donations or someone is racing me for the glory... Well those or it's because the patch is super small and easy... Like offsets only...