The thesis statement should appear very close to the beginning of the paper. Some professors want it in a specific place — often the last sentence of the first paragraph. That’s as good a position as any, but I prefer not to be rigidly formulaic in such matters. In any case, though, the thesis statement should be very near the beginning (in the first paragraph or two).
– Maxine Rodburg and The Tutors of the Writing Center at Harvard University