Q: Can Egg-White Cervical Mucus (EWCM) indicate the exact day of ovulation?

A: EWCM is not a reliable enough indicator to pinpoint the exact day of ovulation. A better way to establish the day of ovulation is taking your temperatures.
You may have had EWCM but that doesn't necessarily mean you ovulated that day. In fact, the 24-day difference signifies more likely that you did not ovulate eaxctly on the first day of EWCM.