NBC in the Constitutional drafts:
June 18, 1787 - Alexander Hamilton suggests that the requirement be added, as: "No person shall be eligible to the office of President of the United States unless he be now a Citizen of one of the States, or hereafter be born a Citizen of the United States." Works of Alexander Hamilton (page 407).
June 27 1787. IN CONVENTION (Vattel's legal work is read aloud during the Federal Convention) "...that an equal vote in each State was essential to the federal idea, and was founded in justice & freedom, not merely in policy: that tho' the States may give up this right of sovereignty, yet they had not, and ought not:In order to prove that individuals in a State of nature are equally free & independent he [Luther Martin] read passages from Locke, Vattel, Lord Summers -- Priestly. To prove that the case is the same with States till they surrender their equal sovereignty, he [L.M.] read other passages in Locke & Vattel, and also Rutherford:" From Madison's Notes on the Convention.
Similar notes on Vattel being read during the convention can be found in the notes of Rufus King and Robert Yates as well.
July 25, 1787 (~5 weeks later) - John Jay writes a letter to General Washington (president of the Constitutional Convention): "Permit me to hint, whether it would be wise and seasonable to provide a strong check to the admission of Foreigners into the administration of our national Government; and to declare expressly that the Commander in Chief of the American army shall not be given to nor devolve on, any but a natural born Citizen." [the word born is underlined in Jay's letter which signifies the importance of allegiance from birth.]
http://rs6.loc.gov/cgi-bin/query/r?ammem/hlaw:@field%28DOCID+@lit%28fr00379%29%29:
September 2nd, 1787 George Washington pens a letter to John Jay. The last line reads: "I thank you for the hints contained in your letter"
https://books.google.com/books?id=vTBIAQAAMAAJ&pg=PA269&lpg=PA269#v=onepage&q&f=false
September 4th, 1787 (~6 weeks after Jay's letter and just 2 days after Washington wrote back to Jay) - The "natural born Citizen" requirement is now found in their drafts. Madison's notes of the Convention
The proposal passed unanimously without debate.
Thank you for your contribution.
Some of the deliberate obtuseness seen in these threads belies an agenda.