The order in which we create culture isn’t hugely important, with one major exception: decide on ideas and beliefs, and then a unified cultural vision early on. This doesn’t have to be first, as having a few ideas of culture can inspire the vision, but try not to go too far until an idea is achieved. If we still can’t decide on one, we’re risking incongruity.
It’s also important to create the social classes so that we know where the group for whom we’re creating culture falls, since this impacts many aspects, including their formality. The rest can be done in random order, but we’ll arguably get the most mileage from greetings, farewells, clothing/accessories, dining, past times, and daily life. It can be wise to keep ideas we don’t use for one culture but associate them with another instead. This helps set them off against each other. Or we’ll use that other one in another world altogether.