I would use Google flights, set up a few alerts with airlines within the network that you prefer to fly with. You can view how to do this by just googling how to set up a Google flight alert. Then you’ll be getting automatic emails for the dates and flights you have selected, and when the price seems right for you book it then. A window this far out unless it’s a sale fare May be a little pricey. Just search around and you’ll get a feeling real quick. Most of the good deals I find are around three months out of your day to travel. Best of luck, and enjoy your time in Buenos Aires