If this is your first venture into fishkeeping, then reconsider keeping Discus. While these fish have certainly never been easier to keep thanks to the development and widespread availability of captive-bred specimens, I still wouldn't recommend them to beginners and they can still be quite finicky.
When keeping discus for the first time, the larger the tank the better. Keeping Discus in pairs on a permanent basis can be done however it is better to keep these fish in a small group.