Paperwork
The three month notice you must give the HSE
Ireland asks couples to notify a registrar at least three months before the wedding. Here is what that actually means.
Irish law requires couples to give a registrar at least three months' notice before a marriage. You do this through the HSE Civil Registration Service, not through your solemniser alone.
The solemniser on this register can perform the ceremony. They cannot skip the registrar step for you. Both have to happen.
If you are not resident in Ireland, you still notify an Irish registrar. Start earlier than three months if you are posting documents from the United States.