The menus are actually running each evening FROM 7pm* not before and they are running concurrently with A la Carte menus. You will be given a choice of choosing from the specific Dine In Dublin Menu or you can choose to select from their traditional menu.
*Some menus are running for longer.
Personally I'm delighted to see that some of the Dine in Dublin offers are for only €15 or €20, as I'd previously thought that the €25 to €30 price range just wasn't much of a special offer in many cases.
I'd recommend L'Gueuleton, Ely, Saba, and/or the Unicorn (only €25!). I'm a little disappointed to see that Le Mere Zou isn't listed.