Might be best to just divide them until you can get the large tank, to stop them from taking chunks out of each other. They would not have much room to swim, which would be bad, but better than them killing each other.
How long is a few months? If it's 2 or 3, dividing them might be a good option. If it's 6-9, I'd say your best option unfortunately would be to sell the fish, and try it again when you can provide them a proper setup.