The marchers, who set out from Karachi on Sunday, left Lahore on Wednesday and culminated its journey on Thursday night in Islamabad, reports Geo News.
The development comes afterthe ruling and the opposition parties reached an agreement to let the anti-government march progress as planned, as long as they protesters do not cross the sensitive "red zone" in Islamabad.
The JUI-F supremo is expected to present his demands at a rally after the Friday prayers, which will also be addressed by opposition leaders.
On Friday morning, Pakistan Peoples Party (PPP) Chairman Bilawal Bhutto Zardari addressed the marchers, saying all opposition parties have gathered at one platform to give a clear message to Prime Minister Imran Khan that the time has come for him to step down, Dawn news reported.
Calling Khan a "puppet", he says the nation is not ready to bow its head before a "selected" Prime Minister and "those who have selected him".
"We are not ready to bow before any selector or dictator... The hub of power is people and not the state."
While speaking to Aaj News on Thursday, Rehman said that it was "for the people to decide what our next strategy should be".
He said the chance of his party giving time to the PTI-led government has "ended", adding that there would be "chaos" in the country if it refuses to resign in the aftermath of his Azadi March protest.
"We have to finally get the resignation from them (the government). And we will fight for it," the JUI-F chief told Aaj News.
Hinting at a sit-in, he said that his party wanted to give the government a time period of two-three days "while sitting in Islamabad".
Meanwhile, all school will remain close in Rawalpindi and Islamabad on Friday, due to the protest march. The Quaid-e-Azam University in Islamabad will also remain closed for two days.
Metro Bus Service between Islamabad and Rawalpindi will also not be functional for an undefined period of time.
Speaking to media on Friday, Special Assistant to the Prime Minister on Information and Broadcasting Firdous Ashiq Awan said that Rehman has been provided with five-star facilities, adding that Pakistanis should hear what his agenda was.
Fazl had announced in June that his party had decided to hold an anti-government long march to Islamabad in the month of October in a bid to topple the government, which he sad had come to power through "fake" elections.
( With inputs from IANS )