They will monitor the pre-election period, will continue at the polling stations during the voting process, stay for exit polls and be present until the results are published.
At this week's briefing Ira Richter, executive director of IOPS.org, said his organization of ISPs has lined up about 25 people who will be participating in various activities to monitor the date-change transition period.
Enterprise Minister Fergus Ewing said the fall was "expected" and said the Scottish government would "continue to monitor these figures closely over the forthcoming period".