I'm relieved to see that everyone is ok with this idea, so far, lol. I'll give it a few more days to ensure everyone gets a chance to comment.
Ltervlet fully explained the way we would transfer characters from SoS to KoS, and I'd just like to add that we would need players to ask to be re-invited to KoS as we can't just transfer the characters when they are offline (and we wouldn't do that without permission anyway). For inactive characters, they will be automatically removed (by Ltervlet, thanks) after 60 days, but active characters need to be transfered by the players themselves.
Please be patient when asking for an invite to KoS from SoS, and it would be wise to ask in the KoS chat channel if anyone can invite you to KoS before leaving SoS. To answer the question about when you can ask for a transfer, there is nothing stopping anyone asking for an invite to KoS now, but I would ask that everyone wait until the weekend so we can be sure that it is what the majority of players want, and so Ltervlet is not swamped (there are more people with invite ability on at weekends normally).
Halish is right that the officers will be keeping SoS as a "spare" guild and we will have our least played characters put there so we can do that. One idea for SoS is that we can use it for crafting members so they can store supplies there, but we would only start buying bank tabs there once we have all the tabs in KoS and LoS, and SoS is clear of characters.