What are the first references to a tradition of fasting before partaking of the Lord's Supper? I recently learned that in Roman Catholicism, it's expected that partakers of the Eucharist will fast for at least an hour.  Canon 919, §1 reads:


  A person who is to receive the Most Holy Eucharist is to abstain for at least one hour before holy communion from any food and drink, except for only water and medicine.


I'd like to know how long this practice has been around.  What is the origin of requiring a fast of some duration prior to the receiving of communion?

I know 1 Corinthians 11 is often referenced as a basis for this practice, but I find it insufficient in itself.  Verses 33–34, for example, could be read to suggest that one should eat prior to communion.  Thus I'm looking for clear evidence of this practice in the post-apostolic church.

Note that this is different from the twice-weekly fast in the early church, at least in theory.  I'm not aware of evidence that indicates that those fasts were done immediately prior to taking communion.

Related: What are the reasons for the Catholic Church's law regarding the Communion fast?
This practice is attested as early as the first half of the third century, by Tertullian and particularly Hippolytus.
Tertullian addresses the topic tangentially while addressing the dangers of women marrying non-Christians.  Their husbands will notice their Christian practices, such as fasting before taking communion, and may put pressure on them to stop:

Will not your husband know what it is which you secretly taste before (taking) any food? and if he knows it to be bread, does he not believe it to be that (bread) which it is said to be?
(To His Wife, II.5)

Hippolytus is more direct.  In the Apostolic Tradition, he writes:

The faithful shall be careful to partake of the eucharist before eating anything else. (36)

At the Synod of Hippo (AD 393), the practice is codified in Canon 29 (Mansi, III, 913), and again a few years later at the Synod of Carthage (Canon 28 (Mansi, III, 884)).  And around this time, Augustine indicates that the practice is universal:

It pleased the Holy Spirit to appoint, for the honour of so great a sacrament, that the body of the Lord should take the precedence of all other food entering the mouth of a Christian; and it is for this reason that the custom referred to is universally observed. (Letter 54, VI.8)

Conclusion
Thus we have evidence for the practice of fasting before the Eucharist as early as the beginning of the third century, and by AD 400 we see it being widely observed, at least in the Western church.