A past Facebook status update: So they don't have books in the Bronze Age. *Goes back through and replaces all mentions of 'books' with 'scrolls.'*
I recently heard an author of historical romance asked, "Do you do your research before you write your book, or as you write?" It seems like a perfectly reasonable question, and for the most part, it is - but the answer, at least for me, is "both."
Writing a novel set in a magical Bronze Age was a research challenge, filled with minor epiphanies and moments of "Wait, they don't have that!" (like soap, saddles, and pants.) It also included editors pointing out things that wouldn't grow on Santorini, or wouldn't yet be cultivated (you know, like carrots.) And having never been to the Mediterranean, I had the strangest thought of, "Does the Mediterranean Sea have tides?" Turns out, the tides are so small as to be unnoticable (although the moon does, yes, actually affect the sea enough to technically give it tides.)
Research doesn't always happen at the beginning of a story (and yes, having never written or even significantly studied this era of history, I had to do a lot of initial research.) Sometimes, it happens in the middle of a paragraph, or even in the middle of a sentence, when I realize that I need more information. Now I'm onto a new novel, one set in a more modern age, but I still come across the same challenges. What sorts of trees grow in Southern China? How long does it take to get to China from Japan by ferry?
So just because you've completed your initial research, laid out your setting in perfect details, and carefully chosen historically or locationally accurate names, doesn't mean you can put aside your books entirely. Some days will involve as much research as writing, and usually over the oddest subjects. ("What's a good, very casual Japanese restaurant for a small, semi-private discussion?" and "How long would it take a large wall of glass to cool enough to climb over?" - thanks all my friends for helping with the answers!) The bright side is that every moment is filled with learning!
If you want to keep your book feasible, be prepared to research continuously, and don't be afraid of the internet - having a second monitor has been invaluable to me, allowing a quick Wiki-check without minimizing my writing. And, of course, having friends who know about the subject really helps.
What are some of the oddest things you've found yourself researching for a story?