The 46 trucks will be the first to reach the besieged enclave since mid-February, despite a recent UN-backed ceasefire and short, daily truces ordered by Russia.
At least 719 people have been killed in that period, many of them children.
Fourteen civilians died in government air strikes overnight, activists say.
Another 5,640 people have been injured in the Eastern Ghouta, an agricultural region east of the capital Damascus, according to a local opposition-run health directorate.
If the convoy of trucks are able to deliver their food and aid supplies to the 27,500 people it is supposed to, despite nearby shelling, it would be a "significant beginning", according to the BBC's Jeremy Bowen.
More about: Syria