For almost all plants, you should water them only when the top inch or so of soil feels dry. An easy way to check if your plant needs watering is to follow the.
The container should be roughly 6 inches deep. The width of the container depends on how many bulbs you are planting. Hyacinth bulbs in pots can be spaced more.
The conventional advice is to water early in the morning - before or right after dawn - to allow the water to soak in and be absorbed by the plant tissues.