Donald Jr also spoke about how his father's election had touched him personally.
'Eric and I and Ivanka, we've been in every small town in this country. We've met so many incredible people - people that have journeyed from all parts of the country to be able to be here to watch this event,' Donald Jr said.
'Literally just seeing some of them along the way and running into them here now, it's really overwhelming. And I'm not a person that tends to look at those things that kind of way. It's truly special when you think of the significance and the history.'
Donald Jr was calling from Blair House, the president's guest house where president-elects traditionally stay the night before their Inauguration.
'We're in Blair House now and thinking of him looking at the walls and all the things that happened here and the people who stayed here and the major decisions that have been made here, and that's before we even get to the White House. It's like something I've never felt before.'
Donald Trump Jr will be standing behind his father at 11:30am this morning outside the Capitol Building, as he takes the oath of office and then gives his Inaugural Address. The newly sworn-in president and his family will then watch the Inaugural Parade from a covered area outside the White House.
Trump was up early Friday morning - going about business as usual by tweeting.
'It all begins today!' Trump tweeted at daybreak. 'THE MOVEMENT CONTINUES - THE WORK BEGINS!'
Ebullient Trump supporters flocked to the nation's capital for the inaugural festivities, some wearing red hats emblazoned with his 'Make America Great Again' campaign slogan. But in a sign of deep divisions Trump sowed during his combative campaign, dozens of Democratic lawmakers were boycotting the swearing-in ceremony on Capitol Hill.
While Trump came to power bucking convention, he was wrapping himself in the traditional pomp and pageantry that accompanies the peaceful transfer of power. The president-in-waiting will attend church with his family Friday morning, then meet President Barack Obama and first lady Michelle Obama for tea at the White House. The Trumps and the Obamas will travel together in the presidential limousine for the short trip to the Capitol for the noon swearing-in ceremony.
Trump supporters started lining up at security checkpoints before dawn to take their places in the quadrennial rite of democracy.
'I'm here for history,' said Kevin Puchalski, a 24-year-old construction worker who drove from Philadelphia to attend the swearing-in. 'This is the first president that I voted for that won.' His big hope: Trump builds that promised wall on the U.S.-Mexican border. 'Keep the illegals out,' he said.
Protesters, too, were out early, some wearing orange jumpsuits with black hoods over their faces.
Eleanor Goldfield, who helped organize the Disrupt J20 protest, said demonstrators hope to show they will not be silent throughout Trump's presidency. She called Trump supporters 'misguided, misinformed or just plain dangerous.'
Trump aides said the president-elect had been personally invested in crafting his inaugural address, a relatively brief 20-minute speech that is expected to center on his vision for what it means to be an American. Spokesman Sean Spicer said the address would be 'less of an agenda and more of a philosophical document.'