The decision to move, or the decision to move at that time?
The latter is a combination of reasons:
Firstly - the character transfer sale ends next week. There will still be the ability to buy realm transfers, but it will cost more. Yes, you can buy tokens now at the discounted price, and hold onto them, but some people will not want to purchase tokens until they know for sure, that we're moving (we are, but until it happens, some won't want to risk the money). Also there will be some people who won't be reading discord, website, facebook or MotD .. the guild will move one day and it will be all "omg .. I didn't know about this" ... having the sale still on, also benefits those people.
Also .. I normally have regular guild recruitment going pretty much all the time. Now that we are moving, I cannot recruit for the guild on Lightbringer. But we don't currently have a guild on Tarren Mill either, so I can't recruit for that either. So .. the ideal time to go, whilst the sale is still on, and keeping only a short length of time between the decision and the move, is this weekend coming.