The bank on Sunday extended the deadline for exchanging the old currency by 10 days, saying some 30% of old bills still remain in circulation.
While many praised the longer changeover time, critics say authorities should have stuck to the original Jan. 31 deadline for the currency swap.
Abuja resident Prince Eromosele said the CBN succumbed to pressures from the political class.
"I had this feeling that it might be extended because of the APC and PDP presidential aspirants' reactions," Eromosele said. "If I'm being honest, I'm very, very disappointed with the CBN governor. Thirty-first is 31st, Nigerians had already started adapting to it already, we just have to make rules and abide by them."
The central bank said the gesture was to allow more citizens to exchange their old bills and reduce the risk of losses.
The CBN also approved a seven-day window after the new deadline, during which citizens still holding the old currency must then deposit the bills directly to the central bank.
Nigeria will hold general elections next month.
Ndu Nwokolo, a lead partner at public policy think tank Nextier, said the currency swap is beneficial, especially as Nigerians prepare to head to the polls.
"I think what CBN did was to look at some critical variables around the system in terms of the present circumstances in the country,” he said. “You have an election going on, you have the pressures from political parties, you have the ongoing fuel crisis, these things are all drivers, and the economy is interwoven. So, I think they looked at the entire situation."
The measure, launched in October, saw the redesigning of Nigeria’s 200, 500, and 1000-naira notes.
The move is meant to combat counterfeiting, encourage more online payments and reduce crime, including the practice of vote-buying using stashes of accumulated cash.
Some 40% of Nigerians do not have access to bank services. Nwokolo said the exchange swap is an opportunity to correct that.
"It could be another opportunity to start looking at how you start getting these people into the legal banking system,” Nwokolo said. “You don't want a situation where the politicians can cash in on that and cause a kind of revolt against the government."
The central bank has faced backlash from critics opposed to the currency reforms, including some lawmakers.
This is Nigeria's first currency update in nearly two decades.