May I make the following suggestions:
1) Close character creation on all NEW worlds.
2) Offer FREE transfers for the first week to Free Companies ONLY.
3) Second week of new worlds, offer FREE transfers for ALL characters.
4) Third week..open new worlds to all.
5) Add an AFK kicker that would log afk players out after 30 min. AFK.
Also, since this would take an additional 2 weeks, I suggest adding 30 days free time as compensation.
Having the new world open to all initially would not resolve the overcrowding problem, I think that this suggestion would.