Does egg white cervical mucus happen before ovulation or does it mean you are ovulating, if before how long can it start before ovulation takes place?

Mucous not ovulation: In someone who has classic 28-day cycles, the mucous you describe from the cervix does become more abundant prior to ovulation. Because sperm can live for 2 - 5 days in the female genital tract, the appearance of the cervical mucous precedes ovulation and points to the "fertile time" during the cycle. If one is doomed not to ovulate, the appearance of mucous has no meaning.