Cultural is the only one you need to plan for from the start.
This is simply wrong. The point upto when you should decide to go for cultural to achieve a reasonable win is when you have the first good opportunity to beeline Liberalism (or even just at the point when you discover Liberalism). This is the point to decide because you will want to stop teching then if going for Culture (in favor of collecting gold for $rushes, see below).
You should also have the Pyramids (for US), but these are usually a priority wonder anyway.
You don't need to hog wonders to get an excellent cultural win, because all you need are three religions within your borders and lots of cathedrals. These can be $rushed (if you have the Pyramids) and then you crank up culture to 100% and wait for the win. You certainly don't have to build modern era wonders such as Eiffeltower, Hollywood and Broadway.
It helps to plan for Culture earlier because you can then spam Great Artists from early on, but it's not a prerequisite. Rushing out the Cathedrals and having decent commerce to generate a lot of Culture is enough for a Cultural Victory (you'll still manage to get a few artists after Liberalism if you have farms, of course these will help speed it up).
In GOTM-12 I went for Culture and totally messed up, and still I got my win around 1915. Obviously not exactly a triumph but it was effortless in the end. I did miss out on a lot of wonders, I did generate only a handful of artists through my inability to handle GP farms properly and my military campaigning was a mess. And still I won. I don't go for Cultural Victory anymore because it's too easy and doesn't involve a lot of game play at all during the end game. The recipe is just too simple (establish 9 cities, build cottages, collect/found religions, rush cathedrals, crank up culture slider, end of story; getting to a 1700 win is practice and discipline, but there no suprises involved).
Having said that,
any excellent win (that would get you into the HOF or a GOTM award) requires early commitment and a lot of skill -- not only Cultural.
--Sigi