A successful fantasy draft always has an element of pressure. Owners would like more time to recalculate their draft strategy, but if you give it to them, your draft will become too long. You want the process to be exciting, not tedious. The draft is going to last several hours anyway, so delays should be held to a minimum.
A stopwatch or kitchen timer is a must to keep the draft moving. Some organizers give owners 90 seconds or 2 minutes for each pick. Others allow longer, say, 5 minutes, for the early picks and only 1 minute during later, less critical rounds.
You should also be sure to schedule breaks between at least some of the rounds. Your owners will need to move around, talk about the progress of the draft so far and rethink strategy. Bathroom breaks are also welcome.