Assembly members will vote next month on whether there should be a referendum on further powers.
But First Minister Carwyn Jones refused to say whether the vote would be the "trigger" resolution to formally start the process towards an autumn poll.
The 9 February vote would definitely "move the process forward", he said.
He said he needed to consult opposition parties to ensure the required two-thirds majority needed for a full resolution could be achieved.
It was unlikely that the formal order allowing the referendum would be able to be passed through parliament before it was dissolved for the general election, he added.
This means the responsibility for ensuring the order is passed through parliament successfully could well fall to a new secretary of state for Wales.
The Conservatives have said they would not "stand in the way" of a request from the assembly for a referendum.
But a new Welsh Secretary may want to undertake further scrutiny on the order, which could make the timetable for an autumn poll impossible to meet.
Mr Jones said a February vote in the assembly would "keep all options open" in terms of the timing of the poll.
The leader of the Conservatives in the assembly, Nick Bourne, has indicated that most, if not all, Tory AMs would vote in favour of a referendum poll, following a debate in the Senedd on 9 February.
Mr Bourne said that although his AMs would be given a free vote, they were all likely to vote in favour of the motion to trigger a referendum.
He reiterated his party's position that there was "no way" the Conservatives at Westminster would block a referendum - whether or not they win the forthcoming general election.
The Welsh Liberal Democrat leader Kirsty Williams also confirmed her party fully supported an autumn referendum.