Check the seed package for varieties. If the seed contains perennial or annual rye it will appear sooner, of course. In fact, under ideal conditions, (85 and moist) Scotts perennial rye in my hands has been a quarter-inch tall after 96 hours.
Seed germination can probably withstand wet and dry--HOWEVER--once the grass is a quarter inch tall I suspect that a few hours of dryness will kill it.
Perhaps I can try this as an experiment. In flower pots.