I had cravings and peed a bit more but I just thought it was my head playing tricks on me.
I agree with Victoria. And every woman is different.
There are really no set answers to either of your questions as each pregnancy and each woman is different. Some get a lot of symptoms, some a few, and some not at all. The most common time symptoms start is after a missed period, usually around 5-6 weeks pregnant.
Missed period (of course :))
Tender/sore breasts
Nausea
Fatigue
Frequent urination
I am sure there are more, but these are very common. Remember, though, PMS and early pregnancy symptoms are usually very similar.