The question really comes down to the grammatical correctness of starting a sentence with a conjunction. That has been proscribed by countless English teachers over the years, but is is as inane as the 'Never Split an Infinitive' and the 'Never End a Sentence with a Preposition' rules. If you use a conjunction as the first word of a sentence, just look at the horrible company you would be keeping: BUT, in a larger sense, we can not dedicate—we can not consecrate—we can not hallow—this ground. - Lincoln, Gettysburg Address AND the Congress may by general Laws prescribe the Manner in which such Acts, Records and Proceedings shall be proved, and the Effect thereof. - Constitution of the United States, Article 4, Section 1 AND she brought forth her firstborn son and wrapped him in swaddling clothes and laid him in a manger; because there was no room for them in the inn. AND there were in the same country shepherds abiding in the field, keeping watch over their flock by night. - Holy Bible, Luke, Chapter 2, Verses 7 and 8. So feel free to use a conjunction as the first word in a sentence every now and then. If it comes to an argument, your teacher will be on one side, while the other side will have the Bible, Thomas Jefferson, and Abraham Lincoln. No contest.