CNN has documented 53 times that Donald made this claim. The first was on March 4, 2023 in a speech to the Conservative Political Action Conference in National Harbor, Maryland where he said:

Before I even arrive at the Oval Office, I will have the disastrous war between Russia and Ukraine settled. It will be settled quickly. Quickly. I will get the problem solved and I will get it solved and wrap it order and it will take me no longer than one day.

Donald Trump