Cumbernauld couple Jim and Ann McQuire and Billy and Lisa Graham from Bankfoot were among 38 people killed by a gunman with links to Islamic State extremists.
Deputy First Minister John Swinney was at RAF Brize Norton for the repatriation.
The UK government said 30 Britons were killed at the Sousse beach last Friday.
Eight bodies were repatriated on Wednesday, with nine to follow on Thursday, including the four Scots.
The Tunisian government said it had arrested 12 suspects in connection with the attack by gunman Seifeddine Rezgui, who was killed following the shooting last Friday.
A national minute's silence is to be held at 12:00 on Friday, one week on from the incident, and there will be a gathering at Abronhill Church, where Mr McQuire, 67, and his wife, 64, were members.
Minister Rev Joyce Keyes said they had been "overwhelmed by expressions of support".
She asked for privacy at the event dedicated to the McQuires, who had only booked their holiday a fortnight before the shooting.
She said: "We have been overwhelmed by expressions of support from those who loved this exceptional couple, and many more messages from those who simply shared in our grief.
"Ann and Jim were a kind and gentle couple who will be sorely missed by our congregation; for their willingness to share their musical talents, for their contributions to the Boys Brigade; and for the fellowship we shared."
North Lanarkshire Council has been flying flags at half-mast, and has opened several books of condolence for the victims.
Perth and Kinross Council has instituted similar moves in tribute to Billy and Lisa Graham, who were in Tunisia celebrating Mrs Graham's 50th birthday, and a candlelit vigil is to be held in Bankfoot.
Mr Graham worked as a turnstile operator at St Johnstone football club in Perth, and the team are to take to the field in their Europa League match wearing black armbands as a mark of respect.
Club chairman Steve Brown said the 51-year-old was "a great ambassador for the club", while the couple's MSP John Swinney said there were "no words that can explain the awfulness of this act".
The repatriations of all the British victims is likely to take several days.
Post-mortem examinations will be carried out before the bodies are released to their families. The UK government has ruled out an inquiry into the attack, but said Scotland Yard would assist the Tunisian investigation.
The four Scottish victims of the Sousse massacre in Tunisia are among nine bodies returned to the UK on an RAF flight.