The re-entry into the Pike River Mine will take place on Tuesday, a family member has confirmed to Newshub.
It was originally scheduled for earlier this month, but cancelled when "unpredictable and unexplained" oxygen levels were found at the far end of the drift.
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It was later found a sampling tube that monitors the atmosphere inside the mine was leaking.
Twenty-nine men died when the West Coast mine exploded in late 2010.
Families will meet at the gates of the mine at 10am, before heading up to the concrete seal - which will be removed for the first time.
Tuesday's re-entry was confirmed to Newshub by Anna Osbourne, whose husband died in the disaster.
"It's a private family gathering at the Pike River Mine portal, where there should be about 30 family members gathered," she said.
"It will be a closed event for families and the agency staff.
"We really wanted it just to be about the families tomorrow [Tuesday], and just a couple of hours without being in the public eye."
Osbourne said families will witness the removal of a 30-metre long seal on Tuesday.
"I'm really nervously excited about it," she told Newshub.
"I'd like to think nothing else will go wrong but I'm totally optimistic that everything will go to plan tomorrow."
Prime Minister Jacinda Ardern said she won't travel to the mine on Tuesday.
"That symbolic re-entry, I think it's appropriate we leave that with the families.
"Re-entry into the drift is going to take a number of weeks and months, it's a progressive piece of work.
"This is an issue that's been managed with the agency communicating directly with families, they've been kept in the loop around when they expect re-entry will occur."
Grey District Mayor Tony Kokshoorn said work at the mine had not stopped despite the "minor situation" earlier this month.
"It will be quite a slow process," he told Newshub.
"How quick they get up is really up to what they uncover on the way."
Minister Responsible for Pike River Re-entry Andrew Little said earlier this month he was disappointed to postpone it due to the massive amount of work that had gone into preparation, but safety had to come first.
"We made a promise to ourselves with the families that we are not going to put any more lives at risk, it is a safety first culture, and when something happens that is unexplained and unexpected then you stop what you are doing and you work out what is going so you can proceed safely."
Newshub.
