I turn off barbarians because it's too random,and I play on emperor/immortal. Sometimes I get a huge advantage, and sometimes I get screwed big time. I prefer a more skill based approach,where if I lose the game, it's my fault, not some random early game novelty.
Regarding the worker, however, I ALWAYS, without any exception, wait until population 2. I play on marathon, and a worker will pump out in 30 turns with pop 1, and 24 turns on pop 2. Not a huge difference, EXCEPT that it only takes 13-22 turns to grow from 1 to 2. That means if you start a worker immediately, you lose 6 turns from the worker build, AND an additional 13-22 turns of the second tile of commerce in research.
At this early stage of the game, two commerce coins are the difference between bronze working in 37 turns and 46 turns. Your choice to build a worker first just cost you 3/4ths of a tech.
Get a worker out after 2, chop rush two settlers, then and ONLY then will you work tiles. Those of you who say "it's only a couple turns to get a farm built, it's no big deal" should really play on marathon, where it takes 12 turns to get that farm built, and you really do see the difference in chop rushing prior to building improvements.
Now, for the second and 3rd cities, sometimes it's acceptable to get the worker out first, just because you have a lot of catching up to do with improvements, and you're not ceasing the population growth of your capital, which is really where you will win or lose the early game.
krozman