The date was set following last week’s resounding vote for strike action by members of Unison, the GMB and Unite.
Unison, which has nearly 100,000 Scottish members, voted 70% in favour of strike action over the three-year deal, worth 2.5% annually.
The unions are demanding a one-year deal worth 5% or£1,000, whichever is greater.
Dougie Black, Unison’s lead negotiator for council staff in Scotland, said the plan was to get the employers back to the negotiating table.
“If that doesn’t happen between now and the 20th, then the aim will be to send a strong and clear message to them,” he said.
Meanwhile, negotiations for staff in England, Wales and Northern Ireland are due to open on Wednesday.