1 Timothy 1:18; 4:14 point to a scenario like Acts 13:1-3
Now in the church at Antioch there were prophets and teachers: Barnabas, Simeon who was called Niger, Lucius of Cyrene, Manaen a member of the court of Herod the ruler, and Saul. While they were worshiping the Lord and fasting, the Holy Spirit said, "Set apart for me Barnabas and Saul for the work to which I have called them." Then after fasting and praying they laid their hands on them and sent them off.
"Prophecy" in the Bible doesn't always nor even primarily refer to prediction of the future. As the above shows, it means delivering an authoritative "word of God" (or any deity) -- the opposite of a "guess" if you will. What Acts 13 says about Saul/Paul, or 1 Timothy about Timothy, is simply that they were divinely appointed, through the prophetic charisma/office within the early church.
I would add that neither Acts nor 1 Timothy need to be "historical" -- the true objective of both stories is to validate the authority of the 2nd century church leaders by tracing their institution back to an idealised early Christianity in which the leading figures were directly appointed by the Holy Spirit; then both Paul and Timothy, as indisputable founders, appoint further leaders (bishops and presbyters, "overseers" and "elders" if you prefer): here's the connection.
Timothy's relative youth (which doesn't make him a "kid" though) may well be part of the scenario: in the founding charismatic times the Spirit acted in extraordinary ways (contrast the ordinary present where the leaders are generally meant to be elders); cf. Elihu in Job, opposing the older men's wisdom with God's Spirit.
Even the bit about wine may have an anti-ascetic intent (like the recommendation of marriage in the same context).
(Guesses of course. We may never have anything but a network of guesses.
Doesn't faith walk on water?)
