Vertical Lists, Bullets

Q. Is it ever okay to start a list with a sentence ending in a period instead of a colon? (“To determine the answer, use the following concepts.”) Does it matter if the list is set off by bullets or that the typesetting is different (by color or font, etc.)? What is the preferred method if both ways are correct? What if it is not a complete sentence? I appreciate the response. Me and a fellow copy editor are at odds.

A. Chicago’s preference is to use a colon, but there are times when a period might better serve. Please see CMOS for details on how to punctuate vertical lists and for examples that include sentences and sentence fragments. If you use a period, the list items should begin with capital letters. (P.S. I am averting my eyes from “Me and a fellow copy editor are at odds”—please tell me that this is just your fun email-writing style, or if it isn’t, that you aren’t editing anything important to our national security.)