how early does pregnancy symptoms show?

While the studies show that egg takes 12 hours of ovulation ( and not more than 24 hours )to fertilize, but the symptoms start to appear only after 7-10 days.The pregnancy symptoms are detected only after the egg implants itself,which occurs only after 7-10 days post ovulation.Also remember,every woman and every pregnancy is different so there's no need to panic if u donot have the signs of pregnancy till much later.

i don't know if i am. my period it due today, and its not yet here. i'll still wait for few days before i take a hpt. it feels like i'm always hungry, that gassy feeling, and acidity.. are those some of sign of pregnancy?