English also told the AM Show that letters had been exchanged over the weekend but he did not have a deal to take to National's board.
"It's quite important people understand the discussion NZ First are having today is another step in the process but it's by no means the final step in actually agreeing a government," English told the show.
Ministerial positions had not been discussed, English confirmed.
Earlier, Peters told Newstalk ZB that the process had been far more complex than he had originally thought it would be.
Peters said he worked over the weekend ahead of the caucus and board meeting in Wellington today to firm up the precise agreements with National and Labour, and contact with them had been "reasonably extensive".
But there had been no discussion on ministerial positions and he made it clear he wants the decision to be made without reference to them.
"The danger of these sorts of talks is when people get ahead of themselves and concern themselves with positions and preferment and things like that and policy gets sacrificed on the way through.
"The last thing we want is for that to happen. That's the fact. We have not talked about it to anybody."
NZ First MP Mark Patterson has arrived in Wellington ahead of today's meeting - saying today's discussions "are not tiddly winks".
Patterson said he wasn't sure if a decision would be made today.
The meeting is being held at Parliament's Bowen House.
Asked what would be front of mind for him ahead of the decision, Patterson said it was an important day.
"We are not playing tiddly winks, are we. We've got to get a sound governing arrangement. And that's what we are focussed on."
The meeting, nine members of the caucus and 12 members of the board, would have an enormous amount of information to sort through, Peters said earlier.
"If we need any further information we have the capacity to quickly call up and sort it out."
Peters said the decision was unique and complex in his political career.
"I've never had a decision to make like this in the context of the potential positive side of it.
"I've had to make decisions in my career which have been 'I'm not going to accept this and I'm going to have to leave and I'm going to have to make a stand here'."
But because of peculiar circumstance it was an extraordinarily awkward and complex situation, which he might be able to explain better in the future.
"It has been much more complex than I originally thought before the election and on election night," he said.
Party president Brent Catchpole said he would be approaching the contest evenly.
"The biggest factor in my mind at the moment is an open mind - keeping it open for everything to be discussed."
And the quality of the deal, rather than the politics of any choice, would be the biggest factor for him.
"It's a big task," he told the Herald.
He defended his decision to withhold the names of the board members - even though such information has traditionally been freely available.
"It came down to the pressure," he said. "I asked members of the board if they wanted to have their names distributed and quite a number of them said no. It was either all or nothing. So I said no."
Peters has said the decision had to be made by an overwhelming consensus of the group.
He has not put a deadline on the decision - but it could run until tomorrow.
The Green Party is ready to hold a special meeting by conference call to approve the confidence and supply deal it has negotiated for a Labour-led government. It has booked its delegates to be ready for the call each night.
Meanwhile former New Zealand First MP Pita Paraone yesterday expressed doubt that his party would support a deal that included setting up the Kermadec Ocean Sanctuary without first resolving Maori fishing rights. The Herald on Sunday reported that one of the Green Party claims in its talks is to get the stalled sanctuary back on the table.
A BRIEF HISTORY OF MMP GOVERNMENTS SINCE 1996
* 1996. The first MMP government was formed by National and NZ First. It took six weeks to negotiate and was a full coalition, with cabinet ministers from both parties. Winston Peters was Treasurer, a contrived position, and deputy prime minister. It fell apart after Jim Bolger was ousted as prime minister and replaced by Jenny Shipley, who lost the next election.
* 1999. Labour, under Helen Clark, formed a coalition with the Alliance but the two parties didn't command a majority in parliament. Clark needed the Greens, who had won seven seats. They agreed to a support arrangement which gave the government sufficient votes on confidence and supply to hold office. The Greens were not part of the government.
* 2002. National was trounced and Labour went into coalition with the Progressives, a splinter of the Alliance, which held two seats. But they were still short of a majority and Clark had the choice of three support partners - NZ First, the Greens and United Future. She negotiated a support agreement with United Future.
* 2005. National came back strongly but Labour again won more seats than its rival, 50 to National's 48. By now Clark was accustomed to running a minority government with the support of the smaller parties, and she negotiated agreements with NZ First, United Future and the Greens. Peters became Foreign Minister outside cabinet, and Peter Dunne Minister of Revenue, also outside cabinet. The Greens had no positions.
* 2008. National, now under John Key, won 58 seats against Labour's 43. Key decided to run a minority government with support agreements from ACT, United Future and later the Maori Party. It was more than he needed and broadened his government. Ministerial positions were given to minor parties but they were not in cabinet.
* 2011. Key was by now a popular prime minister and brought National back with an increased share of the party vote - 47.3 per cent which gave the party 59 seats. It was a simple matter for Key to again sign up the minor parties in support roles and the minority government was able to maintain its stability.
* 2014. Labour's turn to be trounced and on election night National held 61 seats, the first outright majority by a single party since MMP was introduced. But it lost a seat on special votes and Key was again running a minority government with support from his old allies ACT, United Future and the Maori Party. In November 2016 Key resigned and left parliament. Bill English was chosen by National's caucus to take over as prime minister.
* 2017. National, under English, won the most seats - 56 to Labour's 46. But Labour, with the Greens and NZ First, had enough seats for a majority. National could also hold a majority and stay in power, but not without NZ First. Winston Peters was again the kingmaker.
Timeline: NZN