Donald Trump's motorcade has arrived at the New York State Supreme Courthouse in lower Manhattan.

Court is scheduled to get underway at 10 a.m. ET, with Trump scheduled as the day's only witness.

Donald Trump, in New York, had a prep session with his lawyers Sunday ahead his testimony, sources tell ABC News.

Trump's mood during the session fluctuated between fits of anger regarding the case and being "in a good head space," according to sources.

The former president "can be a good witness if he stays focused," one source said.

Former President Trump is due in court to begin his testimony in his $250 million civil fraud trial at 10 a.m. ET.

Hundreds of members of the news media are huddled outside the New York State Supreme Courthouse ahead of Trump's arrival, with some having waited overnight.

After multiple in-court disputes about communications between him and his law clerk, Judge Arthur Engoron modified his limited gag order to cover attorneys in former President Donald Trump's civil fraud trial.

"Defendants may reference my staff as is appropriate to ask about scheduling issues or the management of the trial, which is an integral part of their jobs. What they may not do is to make any further statements about internal and confidential communications (be it conversations, note passing, or anything similar) between me and my staff," Engoron wrote in his supplemental limited gag order on Friday.

Engoron wrote that defense lawyers Chris Kise, Alina Habba, and Clifford Robert made "repeated, inappropriate remarks about my Principal Law Clerk, falsely accusing her of bias against them and of improperly influencing the ongoing bench trial."

The attorneys have raised multiple arguments during the trial that Engoron and his clerk passing notes between each other suggests impropriety and is distracting. Going forward, if the lawyers want to object to communications with his clerk, Engoron advised that they refer to the order as a "blanket statement."

"This gag order is as narrowly tailored as possible to accomplish its purpose, which is to protect the safety of my staff and promote the orderly progression of this trial," Engoron said.

To justify the safety threat, Engoron added that his chambers has received "hundreds of harassing and threatening phone calls, voicemails, emails, letters, and packages" since the start of the trial,

The judge threatened "serious sanctions" for violations of the extended order.

Cushman & Wakefield executive David McArdle, who was hired to appraise the value of 71 undeveloped residential units at the Trump National Golf Club in Westchester County, New York, testified that he also conducted multiple appraisals for conservation easements at the property in 2014 and 2015.

Signing a conservation easement would allow the Trump Organization to give up their development rights and treat the difference in property value as a charitable donation, according to the New York attorney general.

By giving up the right to develop the 71 residential units, McArdle found that the donation was worth $43 million, according to an April 2014 appraisal. A later appraisal McArdle conducted in 2015 landed on a similar valuation of $45.2 million.

But Trump's financial statements from those years appear to ignore the appraisals, valuing the land from the undeveloped units at $101 million, according to documents entered into evidence.

"Based on the supporting data, the only source for the increase in the number of units and profit per unit were telephone conversations with Eric Trump," the New York attorney general alleged in her complaint.

McArdle also testified that he was consulted to appraise Seven Springs, a New York estate Trump purchased for $7.5 million in 1995.

To value the property, which could be subdivided into 24 to 26 residential lots, McArdle testified that he toured the site, consulted a local expert, and spoke with Eric Trump on multiple occasions.

"He had a very high opinion of the property, which didn't surprise me," McArdle said.

His appraisal ultimately determined the total value for the lots in 2014 was $30-$50 million, McArdle said.

But the New York attorney general alleges that appraisal was ignored in Trump's 2014 financial statement, in favor of a "false and misleading" value of $161 million for a portion of the undeveloped lots.