Assuming this as a question of timing, not general hydration.
In the morning, while waking up it can take a while to notice how hungry, thirsty, etc you are. If you are dehydrated, it takes longer to wake up, and to notice you need water. :) Drinking a tiny bit of water will solve that faster.
If you plan on but struggle to eat breakfast, a small glass of water can "wake up" the system so to speak. Helps for some!
you thirsty? -> yes. very important
Usually, not really.
old people may feel less thirst. if you're old, you should hydrate a bit extra, just to be safe
https://health.clevelandclinic.org/drink-up-dehydration-is-an-often-overlooked-health-risk-for-seniors
Are you not thirsty? Think again. Drink water.