When to randomize patients in a randomized controlled trial?

The timing of randomization should be carefully considered in the context of each trial as it has implications for the particular research question answered. In the majority of instances, randomization should be delayed until as close as practically possible to the moment of intervention. In some cases, early randomization may offer certain advantages, but trialists should balance these, including any administrative complexity or inconvenience, against the risk of avoidable protocol violations and avoidable dropout.