A crowd of about 15 supporters sat inside the district court for the sentencing of the 20-year-old, who cannot be named as it might identify his victims.

The defendant sat in the dock and heard Justice John McLaughlin's summary of the case.

The court heard the defendant had been in a six-month relationship which ended approximately one month before his arrest on February 14 last year.

On the day of his arrest he twice instructed a 14-year-old to perform oral sex on him at a Port Macquarie beach. The crown also argued the defendant's instruction to the victim that she was not to tell anyone showed he knew it was wrong, dismissing any claim of a lack of insight. He had told one victim she was pretty, before again initiating oral sex with her and then being interrupted by another adult who called the police.

Justice McLaughlin read quotes from the victims' impact statements which described how their lives had changed since the crimes.

One victim said she felt "weird and uncomfortable" while another said she felt "uncomfortable and scared" after she was touched by the defendant in an intimate area over her swimming costume.

One victim said she had been ostracised at her school, had lost the friendship of the defendant's sister and struggled to communicate with her own parents.

Another victim said she was too anxious to speak outside her home following the crimes, and she found it hard to talk to other students at school.

Justice McLaughlin said there was, "some planning involved in the commission of these offences".

"While he knew they were young, he did not consider their age at the time," he said.

The court heard while some of the victims had refused the defendant's requests for nude photos of them prior to his arrest, one girl had complied via text message.

The Judge said he was of the view "these offences demonstrate a predilection for early teenage girls".

However, he stated, the pre-sentence report showed that if given the right support, the defendant could "successfully overcome" the thinking that led him to commit the offences and "put him on the path to being a productive and good citizen".

The guilty man's former school principal wrote a letter of "unreserved" support which referred to his commitment to charity work.

But it was the statement written by a retired police officer which seemed to have the greatest influence on sentencing.

The retired detective chief inspector wrote in support of the guilty man's character, and said he would be "happily welcomed" into the former officer's home in the future.

Justice McLaughlin said the defendant "accepts what he did was wrong" and had shown remorse.

"His good name, which he worked so hard to achieve, is lost to him," the judge said.

The defendant's mother had given testimony that she had "the best son you could wish for".

There were "excellent prospects for rehabilitation" including employment upon release from prison, the judge said.

Special circumstances were found which triggered a 25 per cent reduction in sentencing.

Four counts of having sex with a child between 10 and 14-years-of-age came with concurrent sentences of two years and six months, with non-parole periods of nine months. Rolled into the time served were six-month sentences for two counts of aggravated indecent assault.

Including time served since being arrested on February 14 last year, the guilty man will be released on July 13.