Wait until it stops raining (i.e., Sunday), since at the moment highways are being closed here and there, traffic is clogged, and visibility sucks. Find a way to check Caltrans reports on closures before you get too carried away with plans (for example, [http://www.dot.ca.gov/hq/roadinfo/do4map.htm]
I assume you've got a good map; if not, buy one. When the skies clear, head either north or south on the Coast Highway (CA 1). Deviate at will. That will give you a chance to get used to some of the local riding subtleties, like driving on the wrong side of the road and the fact that (unlike India), trucks and buses will not deliberately try to run you into the ditches.
I trust you've also got a guidebook. If not, buy one. 3-4 months is not a lot of time, and there are countless interesting places to see. I'm not going to start listing them, since I don't even know what sort of stuff interests you. At any rate, you're going to have to winnow the possibilities from essentially infinite to somewhat within the realm of possibility.
When you're ready to head out, I agree that a generally counter-clockwise approach will work best; it's still winter up here in the north. You'll still need to watch the weather forecasts carefully, since winter weather sometimes persists even in areas of the south for another month or two, but your odds are better that way. Pay attention to the locations of mountain ranges and passes; even a bit of elevation gain can mean snow and ice, and even a bit of snow or ice can definitely ruin your day.
Getting into and out of major cities will probably be your biggest hazard. Freeways can also be very disconcerting, especially in California. Try to stay off the major ones at first.
Note that the Coast Highway through Big Sur (south of Monterey and Carmel) has been cut by a major slide. You should ride this road, but you'll have to approach from both directions, turning around at the closed portion. You might find the closure a blessing, since there'll probably be little traffic. It's a glorious ride, especially when there's not a lot of competing traffic.
By the time you arrive in my neighborhood in the far north and west it might be springtime. Give a shout.
Hope that helps.