To prepare for the merge, Ramaja will be experiencing an hour-long downtime period, after which players will not be able to declare war on others. The actual merging of servers itself should take approximately two hours, though the devs state it could be longer and announcements will be made in that regard.
Content retrieved from: https://massivelyop.com/2022/02/05/new-world-announces-new-server-merge-for-february-8-confirms-more-merges-coming-soon/.