When the programmed delay is much larger than the internal propagation delay of the device, the delay from rising EN_ to OUT_ is the same as the delay from rising IN_ to OUT_. The formula can be found on page 11 of the datasheet (rev 3 1/07):
t_DELAY = (V_TH-CDLY/I_CH-CDLY) * C_CDLY + 35 * 10^(-6),
where V_TH-CDLY = 1V, I_CH-CDLY is 0.25uA, C_CDLY is in Farads, t_DELAY is in seconds.