Why should I flush or wait to add nutrients when into bloom?

My question is: why should I wait to add bloom nutes or flush after removing a plant from veg? More specifically, what are the consequences of not doing that and just adding bloom nutes to your rez on the first day of flowering? Right now I give the plant regular water for two days and nights then add bloom. I use to add bloom nutrients on the first day of flowering, can this shock the plant?

Flushing is being done after flowering, its mainly for which that its ready to harvest, so we do flushing before three days of harvesting,
when we do flushing the plants produce chlorophyll, when we do flushing with water the this makes the plants vascular system clear.
its better if we do water flushing before 2 weeks of harvest. There is a huge different between a that if a plant is flushed its like an smoking leaf, and if its not flushed its like a smoking bud.

Okay, thanks for the advice. I read in another forum about flushing grow nutrients and didn't know if it had a marked difference. Although, what do you mean by smoking a leaf vs a bud?