a lot of wishfull thinking in this thread.
the simple fact that your next to a warmongering civ that declares war while you are in the middle of your settler rush is enough to spoil the plans that i read immediately.
i'm testing a few of these suggestions right now. 3 workers within 20 to 40 turns? i met Milan at turn 10 and he didn't have a worker. The next civ i met was at turn 20 . . . . . no worker in sight. Moving on.
So what you can do is reload the map and send your warrior straight to the nearest civ once you know where it is. That makes a huge difference as sometimes you'll just send the warrior off towards the coast and other times you'll get lucky and send them the right way and be able to get a worker turn 10 or sooner as the AI will still be improving tiles.
For city-states, they usually get a worker at turn 20ish, so at that time you want a scout to be back near the nearest city-state to your capital, ready to snatch a worker that will come to improve a luxury. Keep that scout in range of that same tile, but not touching the city-state border, and you will get a fresh worker every 15-20 turns.
Same goes for AIs. Once you steal a worker from a luxury, pillage it ( if you can survive ) and then park your warrior in range of that luxury waiting for more workers. On deity they have 2 workers to start I believe, so you can snatch both, and they pump out replacements like crazy. Sadly the AI often keeps all their warriors near their cities so it can be tricky to steal a worker without your warrior dying.
Once they are ready to peace out, you can even do a double steal sometimes with a warrior and a scout, and then you peace out.
Now the other war to get workers is to cruise around the map clearing barbarian camps. Those are the workers you get around turn 40-50 to round out your worker pool.
Is you can't steal at least one worker by turn 20, you've doing something wrong or are being very unlucky.
Getting two by turn 20 is harder, getting 5-6 by turn 50 is pretty lucky, but easy by turn 80-90.
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As for warmongering neighbors, it depends. Very few civs will rush you for no reason. That's mostly Attila, Shaka and Montezuma. Those guys might just attack you out of nowhere on turn 50-60 no matter what, so never forward-settle them unless you can settle a 1-tile choke point. That's the only way you'll defend against 10 battering rams on turn 70, other than bribing them to attack someone else.
If you're not next to those guys, it also depends. Some civs are peaceful, like Morroco and Ethiopia. You can settle in their face and they won't do anything about it. But some are more much likely to hate you A LOT, like Japan, America and England. Don't ever forward-settle them because they'll build an army and send it straight at you and they will be hard to bribe, unlike shaka and attila who will declare war for almost nothing on anyone even if they don't like you.
England would take like 5 times more gold to bribe away from you if you forward-settle them.
But anyway, generally speaking, the AI is far enough that they don't bother you. Once you're done with national college, you can build 4-5 archers in the capital while you research education, that's usually enough to defend yourself and it has the bonus benefit that they can go clear barbarian camps for city-state quests and free captured workers.