Seeking Culbert Families in ireland

I am located in the U.S.A. and am researching the Culberts worldwide and have a database of almost 23,000 individuals, including non-Culbert spouses and their parents.  My research is registered with the Guild of One-Name Studies.  My research suggests that Culbert is not a surname variant of any Gaelic clan or family, thus the Culberts must have migrated to Ireland.  I am trying to determine where they came from and when, which requires finding the oldest records of Culberts in ireland.  Since I'm not located there I'm looking for your assistance.  If you have access to old records or know of any Culberts from the period between 1600-1800 in ireland, please contact me.