The mass walkout by National Union of Journalists members is in protest at proposed compulsory redundancies at the company, and is due to begin at 3pm today.
Staff at the Sunday Herald are due to stay away from their desks all weekend to hit deadlines there, and the union estimates only three staff out of around 40 will be left working.
A further one-day strike for staff at The Herald has also been called for Wednesday.
Newsquest says it newspapers will continue to be published as normal.
The dispute centres around six sub-editor roles at the Evening Times which were selected for compulsory redundancy.
Herald & Times managing director Tim Blott yesterday said this figure had now dropped to four and then one, but NUJ Scottish organiser Paul Holleran said the information he had was that three staff were still to be redeployed.
He said work was continuing to go on behind-the-scenes to try and achieve this, but there were no formal talks.
He said: “There are still three people who need to be found jobs. If that happens the strike will be off.
“While we welcome the efforts we are running out of time.”
Tim Blott said: “We deeply regret the decision of the NUJ to continue its proposed strike even though the number of people facing compulsory redundancy has now dropped to one out of total of 300 editorial staff.
“This is despite the fact that only 26 per cent of its membership at the Herald & Times voted for such action.
“We are successfully running a 21st century multi-media business with all its competitive challenges. We will continue to publish our newspapers as normal.”
The planned walkout follows a ballot which resulted in 74.3 per cent of those who voted saying they were in favour of strike action, and 87.3 per cent favouring action short of a strike.
However a postal strike was blamed for a low turn out. At a meeting yesterday the union said a show of hands had seen 150-2 in favour of a strike.