Third Army Chief Lt Gen Preecha Chan-ocha, the younger brother of Gen Prayuth and a member of the NLA said the NCPO leader urged members not to "disappoint" the public.
"He stressed military NLA members must not take naps, play on the Line [mobile phone] application or play with other social network apps during NLA meetings," he said.
Gen Prayuth said the process to establish the National Reform Council (NRC) will kick off on Saturday. Applications for the NRC must be made by Aug 14.
Eleven committees will be appointed to nominate 550 applicants, which the NCPO will whittle down to 173 members. Another 77 members will be selected to represent the provinces, for a total of 250.
Members of the military and police force dominate the interim parliamentary chamber. They are widely expected to appoint Gen Prayuth as prime minister.
"There's no need to lobby for the vote," said one military member. "We can just look at each other's eyes; we know who we will vote for."
While opinion polls and NLA members have backed Gen Prayuth to become prime minister, the activist monk Phra Buddha Isara said yesterday Gen Prayuth is not suitable for the premier post.
"Many people back Gen Prayuth as the new prime minister, but I feel that it would be disgraceful," Phra Buddha Isara, co-leader of the People's Democratic Reform Committee, wrote on his Facebook page.
"Gen Prayuth always tells us he doesn't want power but only wants to help the country, and I'm happy that he's following His Majesty the King's advice," he said.
In his view, Panadda Diskul, permanent secretary in the Prime Minister's Office, was the most suitable candidate for prime minister because he is clever, prudent and knows the civil service system well.
Gen Prayuth, when asked yesterday about speculation over his premiership, merely flashed a smile at reporters and raised two fingers as a sign of victory.
Meanwhile, former army chief Gen Anupong Paojinda, acknowledged yesterday he would become a minister in the government, but declined to give more detail.