the flood should last until the table is filled then the float valve kicks it off, then it drains.
how often you flood is up to your plants you have to figure how fast they dry. depends on the medium your growing in as well. flood, then wait 2 hours to see if your medium has gotten dry, if it has then set it to fill every two hours and so on. (if it drys every 3 hours then set your pump to kick on every three hours.