You can restore to any point in time during your backup retention period. To determine the latest restorable time for a DB instance, use the AWS CLI describe-db-instances command and look at the value returned in the LatestRestorableTime field for the DB instance. The latest restorable time for a DB instance is typically within 5 minutes of the current time.
http://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/USER_PIT.html