I agree with Tom and CruiseDad-- make a visit to the maitre d' your first stop, even if your TA has called Carnival beforehand. He is usually at the desk just inside one of the main dining rooms. This may be noted in the Carnival Capers you will receive upon boarding, but it wasn't listed on our last Carnival cruise. We went to the dining room anyway, and there he was. And, as CruiseDad stated, mention the reason you'd like the table for two.
And, happy 30th anniversary to you! What a wonderful way to celebrate.