It varies from seminary to seminary. Most now require 1-2 years of pre-theology. (for those who have a B.A. degree but lack Latin or Greek), then, 4 years of theology. Some diocesean seminaries have a year of spiritual formation, similar to the novitate for candidates. Many young people do not know the basics of their religion, and have to be taught the truth, not the baloney they were taught as children. (ie., the Eucharist is merely a symbol, that Christ didn’t know that He was divine until the Crucifixion, etc.) If you have any questions, ask a priest.
