The same strategy applies. The only difference between immortal chariots and regular chariots is 1) their ability to reinforce position and 2) their bonus against archers.
1. We don't use reinforce position in this strategy since we are on the offensive, so it does not make a difference.
2. The bonus against archers helps, but it is not necessary as the only thing that can consistently stop chariots are spearmen. You can overcome archers using regular chariots too, the difference is you will have more losses. However since we aim to produce the maximum number of chariots anyway, this does not change the strategy or build order.
The guide mentions 2 workers (one for each city), or even 3 if there are a lot of forests. Generally 2 is enough as you will be done clearing all forests before 1000BC anyway so IMO the 60 hammers needed for a third worker are better spent making 2+ additional chariots at 30 hammer each. Actually more than 2 since a worker stops your growth, and you might be able to get an extra whip (thus chariot) by skipping the third worker.
I think the best moment to make a third worker is after 1000BC and your initial attack, since making an extra chariot at that point won't make a big difference because it has to go all the way to enemy territory. It is generally at that point that I start thinking about growth, making granaries, barracks in second city, etc.
This usually means you waited too long to attack. In my example when I hit with 15 immortals he had exactly 2 spears. You might want to check with your build order and see if you can speed it up somewhere. Using the BO in the guide and settling your second city near the max of forests makes a big difference.
Also you should attack sooner if you see an opportunity. If the AI founds 3 cities very quickly (REXing), has no copper, and not yet done with bronze working, it generally means you can attack sooner with your first handful of chariots. Especially with REXing... since the AI on immortal starts with 3 archers, and if it makes cities fast then they are spread out and you can easily snatch the capitol.
@mirthadir, solid advice there. I will add a few of those tips to the guide shortly.
My mistake, I read warrior or second worker as your second worker. Third worker is for axe rushes, where 10 to 20 worker turns building roads to your enemies detracts from chopping significantly.
Warning: the rest is details concerning high level efficiency
Second worker in the first city is better than worker first in second city, unless you're skipping the barracks in the second city.
First, it's faster, so more worker turns.
Second, your first worker is going to improving your second city linking it to your first city, so if you don't build a worker in the first city, it may grow into unimproved tiles before worker #1 can return.
Third, and most importantly, it maximizes yield. Where you build your worker is a choice between growing from size~ 3 to 4 in your capital or growing from size 1 to 2 in city #2. Your capital is working 1 to 2 mines, so the food to hammer ratio* is far inferior to the city #2 growing off one improved food resource. Also growing to size 2 takes less food.
*The food to hammer ratio is important because hammers in barracks/chariots does not increase your production and as such are "wasted" in the short term, whereas food makes you grow, which means more production. Therefore it's preferable to build workers in a low food to hammer ratio city, and grow in high food to hammer ratio cities. I hope this makes sense.
Deciding at which size to stop growing is important too. Say you're size 4, and you're +2 food while working mines. Do you reallocate to grassland forests to grow faster, do you grow normally, or do you switch to plains/mines to stop growth? In the long run, if you can work an extra mine (+2), how many turns will it take to pay itself back in terms of hammers, and will you even have that much time before you attack? Yes you could whip it off, but you could whip at size 4 and not have an unhappy citizen. You can also skip a garrison if you stay at size 4.
And this is more relevant for axe rushes, but sometimes you want to freeze reinforcements by sending a lone unit to one of their other cities. Even workers can distract them if they don't have roads. And if you're really afraid of spearman counter-attacks, make an archer.
Also in rushes too much food (as in say +10 food) isn't useful, since you can only grow to 4/5.
