Page numbers in musical scores, like those in books, are placed on the right when are odd and on the left when they are even.
When the music begins on the right, as is most often the case, the page number is usually omitted and no title page is required.
When the first page is on the left, however, best practice dictates that the page number (2) appear on the page. In addition, a title page containing the title, subtitle and composer's name should be inserted at the beginning of the document. If it is a part, the instrument name or names should also appear on the title page.
For front side only, unbound scores, consider centering the page numbers.