Here is the Collect for Wednesday of the 3rd Week of Advent.
Praesta, quaesumus, omnipotens Deus,
ut Filii tui ventura sollemnitas
et praesentis nobis vitae remedia largiatur,
et praemia aeterna concedat.
This prayer was in Rotulus 6 published with the Veronese Sacramentary. It was in the Gelasian Sacramentary.
It is interesting that this is more or less the Collect that is in the 1962MR, though changed. I add some emphasis.
Praesta, quaesumus, omnipotens Deus: ut redemptionis nostrae ventura solemnitas, et praesentis nobis vitae subsidia conferat, et aeternae beatitudinis praemia largiatur.
Here is what it looked like in the Gelasian:
Praesta, quaesumus, omnipotens deus, ut filii tui uentura solem[p]nitas et praesentis nobis uitae remedia conferat et praemia aeterna concedat.
There is a parallelism between remedia and praemia. Subsidia and remedia closely related.
Almighty God, grant, we beseech You,
that the upcoming solemn feast of Your Son,
both may lavish upon us remedies for this present life,
and also concede to us eternal rewards.
CORRECTED ICEL VERSION:
Grant, we pray, almighty God,
that the coming solemnity of your Son
may bestow healing upon us in this present life
and bring us the rewards of life eternal.
may the coming celebration of the birth of your Son
bring us your saving help
and prepare us for eternal life.
What comes to my mind is the prayer that the priest says silently as he purifies the sacred vessels in both the older and the new form of Holy Mass: “Quod ore sumpsimus Domine, pura mente capiamus: et de munere temporali fiat nobis remedium sempiternum. … Into a pure heart, O Lord, may we receive the heavenly food which has passed our lips; bestowed upon us in time, may it be the healing of our souls for eternity.”
The Collect is already directed to the moment of Communion.