Hi, Suppose a person makes Shabbat early (and prays Ma’ariv before shkiah) when yom shishi is a one-day Rosh Chodesh. Should the person include ya’ale v’yavo in his amidah? Thank you so much.

No. He should not say Ya'aleh Ve'yavo in his Amidah, because it's as if it is already the night of Shabbat (Friday night) for him regarding prayers. (Magen Avraham Orach Chaim 419. Mishnah Berurah 267,3. & 424, 2. See Also Boey Kallah 19: http://hebrewbooks.org/pdfpager.aspx?req=39911&st=&pgnum=1&hilite=).