A graduation dinner is a big milestone, but the bill usually lands all at once. If you start scouting venues four months before the season hits, you give yourself the best chance at a reasonable price and your preferred date.
You can manage that $1800 expense by using the Discover it® Cash Back (Discover), which offers 0% intro APR for 15 months on purchases and balance transfers. This turns a one-time hit into manageable monthly payments.
Keep in mind that 0% intro APR is just a window, not a free pass. If you have a remaining balance after the 15 months are up, the card will start charging interest on whatever is left over.