No the day you put them in is the set date. Day one is 24 hours later. I tried the water thing with my clutch from broody Betty, who is broody yet again. Her 2 youngest is only a month and a half old. With the water test, none of the eggs moved at all yet 8/10 hatched. I'm not sure if I myself can trust it. I'm afraid to open the bator and see what's going on, but 5:35 equals exactly 21 days after set date.... Still nothing.