I've done it enough times now that I can offer some more guidance on what to do. This is what I'm currently thinking is optimal, but I'm dying to know if somebody else has another plan that is consistently better.
Great People: Produce the following Great People in this order. Your own tech research should be going fast enough that they can be used as fast as they pop out, but if you're behind then just save them for a turn or two- don't pop them on something else.
- Great Merchant on Currency
- Great Merchant on Metal Casting
- Great Merchant on Civil Service
- Great Scientist on Education
- Great Merchant on Machinery
- Great Merchant on Printing Press
- Great Merchant on Guilds
- Great Merchant on Banking
- Great Artist on Nationalism
Do I think this is a lot? You bet. I haven't been able to pull it off unless I had a map where I could quickly get two separate Great Person farms running. Each is going to need to eventually handle 6 specialists even if it runs a food deficit to do so. It's not that common to get a map that will support that early in the game when you need it.
Tech Tree: There's a core of techs that have to be researched in order to claim Code of Laws with Oracle. You need to focus on keeping Workers busy
and trying to get Oracle built as fast as you can. So the order of these techs is up to you based on how you're playing the early game: Mining/Bronze Working, Mysticism/Meditation/Priesthood, Agriculture/Wheel/Pottery/Writing.
After this period you should be able to progress down the following path in this order: Monarchy-> Mathematics-> Philosophy-> Paper. Mathematics must be finished before you can use the GM on Civil Service and the GS on Education. Paper must be finished before you can use the GM on Machinery and the GS on Education. Somewhere in this queue you can slip Alphabet. I would hold off on Alphabet as long as you can so that its relative price goes down and so that the AIs will have enough things that it is worth trading for them. It's not hard to end up in situations where each tech you have is worth 5x what they have in beakers, forcing you to make very lopsided trades. I haven't had any problems trading for Iron Working, Animal Husbandry, Hunting, & Polytheism, with Calendar & Construction coming later. You can also easily get Fishing & Sailing, but Sailing is going to block the GM path after you've bulbed Metal Casting, so if you either started with Fishing or find you need it, try to trade for Sailing as well. Sailing is a very common tech for early AI research so it should be very easy to pick it up.
After Paper then you have the following techs, not in this order: Feudalism, Gunpowder, and Liberalism. Start these but do not finish any of them except Gunpowder. Based on your speed of producing Great People you'll often be filling one or more of these with beakers to mark time while you wait to bulb a key tech. After the GM has been used on Printing Press you can then finish Feudalism to allow the next GMs to go down the Guilds/Banking line. It's unlikely that you can completely bulb out Printing Press and Education, so if you're really running behind on the GMs you can stick a turn or two researching each of those if you have to. But Gunpowder/Feud/Liberalism should be more than enough to cover this kind of emergency. Again, don't finish Liberalism until you can get Replaceable Parts as the free tech.
After Liberalism either finish Rifling right away or focus on getting Nationalism. You need Literature, Drama, and Music before a GA can be spent on Nationalism. If you are going to be the first to Music, then you're getting a bonus. If you pop a GA on your own in short order, then you could even burn him on Music to use the subsequent free GA from Music on Nationalism. Or research Music totally on your own and save them both, as I've been finding on Noble/Normal/Standard it takes 2 GAs to totally bulb Nationalism. Anyway there are lots of combos here- Use one GA on Nationalism and finish yourself, use none on Nationalism and save them both for Military Tradition, whatever. I made a mistake in my earlier commentary, you need Horseback Riding for the GA line, but only after Nationalism and before Militray Tradition. So HR is not required to pop Nationalism with GAs. Either way this is also something not too difficult to pick up in trade (at least on Pangea maps). Of course if you're getting impatient you can skip doing anything with GAs and just research Nationalism & Militray Tradition yourself when you're done with Rifling. In this case you might want to be starting work on GSs to help push you down the Artillery line. I've usually been stopping after I complete the opening but I should go on to find out what my earliest Artillery date is. You might be able to have Artillery out while your opponents are still dealing with Knights & Longbows, however Chemistry isn't that hard to pick up so it's likely going to be Artillery vs Grenadiers.
There are 5 turns of Anarchy created: 4 civics changes plus selection of a state religion to collect the pacificsm bonus. Spir/Philo helps a lot in this! Beyond that you may be forced to wait a few turns so that you can make 2 civics changes at a time instead of just 1. If anybody else had luck with this or a more effieicent plan I'd love to hear your results.