Lent is a season of preparation. Pentecost (50 days) is a season of waiting. It is tied to the Jewish feast of Shavuot, seven weeks after Passover, marking the wheat harvest.
In Acts, we learn that Jesus met with his disciples several times in the 40 days after his resurrection. Before He ascended to heaven, He told them to wait.
Acts 1:4 (NASB)
Gathering them together, He commanded them not to leave Jerusalem, but to wait for what the Father had promised.
As farmers eagerly wait for harvest, the disciples waited for the Spirit.