Syed Zahid Raza, the deputy Pakistani ambassador in Jakarta, told AFP the convicts, who include a Pakistani, could face the firing squad around midnight Friday after today's meeting between Indonesian officials and diplomats to signal the start of the countdown.
Nationals from Pakistan, India, Nigeria and Zimbabwe are expected to be executed alongside Indonesians. Officials say no Europeans or Australians will be included in the third round of executions under President Joko Widodo.
But Widodo has insisted Jakarta is fighting a war against drugs and traffickers must be harshly punished.
Authorities have been stepping up preparations in recent days, with several death row drug convicts transferred to Nusakambangan prison island -- where executions take place -- and security strengthened in the area.
Fourteen prisoners have been placed in isolation cells on the island this week, state-run Antara news agency reported, a step normally taken ahead of executions.
Raza said Indonesian officials had given the notice period at a meeting in Cilacap, the town closest to the prison island, which included diplomats from several countries and lawyers.
It is a legal requirement in Indonesia to give a minimum notice period of 72 hours before executions, and authorities typically put people to death just after midnight.
The attorney general's office, which oversees executions, would not confirm any details but spokesman Mohammad Rum said: "The time is approaching because we are making progress day by day."
Pakistan has raised concerns about the looming execution of its national, Zulfiqar Ali, saying he did not receive a fair trial. Rights groups have claimed Ali, sentenced to death in 2005 for heroin possession, was beaten into confessing.
