Dublin is all about the quiet corners of the city, like the Trinity College library, before you head west to see the Cliffs of Moher. Booking four months out during the shoulder season keeps prices lower and the crowds manageable.
If you want to spread the $2400 cost of this trip, you can use the Citi Simplicity® Credit Card, which offers 0% for 18 months on purchases and balance transfers from date of account opening. This lets you pay off the trip in manageable chunks.
Remember that the 0% intro period is a hard deadline, not free money. If you have a balance left on the card after the 18 months are up, the bank will start charging you interest on whatever you still owe.