This template allows you to enter the month, day, & year you're looking to convert to a Date/Time Format in SFDC & will produce the text for you to copy + paste.

"Unless formatted properly for the API to accept them, users may have trouble importing changes to the "Date" and "Date Time" Data Type fields when the corresponding values in the CSV file do not have a specific formatting or correspond with the org's time zone settings.

Refer to Data Types Supported by Data Loader for all of the supported formats that are unique to Data Loader."