Ramdev aides said he would reach the capital from Gujarat later on Wednesday, and he alone would announce whether he would go on fast or not.
Thursday will mark the 70th anniversary of Quit India movement.
Ramdev supporters have already begun gathering here for a show that comes close on the heels of social activist Anna Hazare's surprise decision to wind up Team Anna.
Hazare has said he will lend his support to Ramdev but it is not clear if he will actually make it to Ramlila ground.
"Our agitation will begin from Aug 9 but people will start gathering today itself," aide S.K. Tijarawala told IANS at the sprawling ground even as workers erected tents and makeshift toilets.
Metal detectors have come up at entry and exit points to screen visitors, who are expected to flood the ground in the heart of the city. Green colour carpets are being laid.
Colourful posters of Ramdev have come up in and around the site. Workers also drained out rain water from Ramlila ground.
"This is the first and last chance for the government to act on black money," Ramdev thundered Tuesday in Gujarat.
According to Tijarawala, around 5,000 volunteers will work round the clock to ensure that nothing went amiss.
"Around 60 CCTV cameras will monitor the grounds. In addition, metal detectors and baggage scanners will be placed on all the entry and exit points," he said.
Delhi Police have given the organisers permission to host 30,000 people a day.
The yoga guru had staged a similar protest at the same venue in June 2011. But a midnight crackdown by Delhi Police ended in bedlam, leaving a woman dead. Ramdev was then forced to leave Delhi.
The yoga guru has been allowed to hold the ground till Aug 30.