What are the rules for GvG fighting when you change guilds? What is the time outs and when does the timer start?
its 96 hours (4 days) from the last action in gvg before you can take action in the new guild when you switch. If you did not do anything in gvg for the last 4 days and join a new guild, you can do gvg actions right away in your new guild.
Above answer about 7 days is not for GvG, it's 7 days before you can rejoin a guild that you left or were kicked from. Rejoining a guild has a 7 day wait period, and that has nothing to do with actions in gvg or anywhere else.