I just want to know if i can work or study in CALIFORNIA if i have K1 visa? and when is the right time for me to get a SSN , before or after marriage? I just want to know because I'm not familiar with this things.

you can apply for your SSN from 7 to 10 days after your arrival up until 2 to 3 weeks of the expiration of your I-94. your I-94 expires 90 days after your arrival. I suggest applying for your SSN before marriage. I've seen some people encountering problems when applying after they are married.
yes you can study, but may have higher tuition at public institutions before you have your green card.
to work, you'll need an EAD or Green card.

As far as I have read all over VJ, employment authorization is granted at only certain points of entry. If I recall, people were reporting that JFK airport (New York) is one of these few POEs.

When we crossed the boarder overland (by car - not walking) at the San Ysidro border in California, I figured it wouldn't hurt to ask the border agent processing our entry if my then fiance could be granted her EAD. The border agent looked at me like I was an idiot and told me that employment authorization was automatic with the K1 visa. Then he asked me if I would feel any better if he stamped the back of the I-94 (is that what it was called?) to which I nodded with a resounding yes please haha.

[edit] Note that as far as I know, this "automatic EAD" with the K1 visa is only good for the life of the K1 - 90 days upon entry. I'm fairly certain that beyond this period, you need to have I-765 Employment Authorization processed.