What happens when I move to a new stake pool? Will I lose rewards?
The switchover is seamless when you move from one stake pool to another and you will continue to receive staking rewards from your current pool until you start receiving rewards from your new stake pool. Every 5 days there is a stake snapshot on the boundary of each epoch. Your staked ada will be active in your new stake pool after two epoch boundaries and you will receive rewards from your new stake pool after the fourth epoch boundary.
You also do not need to withdraw your staking rewards before switching stake pools. See the following link for more information: