It depends on the requirements of the diocese.
To be technically accurate: "Pre-Cana" is a very specific type of marriage preparation. This kind is meetings with the priest and couple. Some different day long seminars are titledpre-cana, but are techinically a different kind of marriage prep program.
There is a "discernment/investigation" part which should be previous to setting a date. This investigates that both are free to marry, and take the foccus to make sure there shouldn't be any need to delay. (Most diocese require a FOCCUS inventory). Then the prep part takes over. There are seminars, weekend engaged encounter, couple to couple mentoring, or classes, depending on the diocese. Also, a couple is usually required to take some sort of NFP class. A few diocese require an additional event called " God's plan for a joy filled marriage" which is Christopher West videos, discussing the theology of the sacrament.
In the classes/retreats, what is discussed is usally communication, finances, sex, adjustment, expectations, family, religion, conflict resolution.
Closer to the wedding date the priest/deacon meets again to discuss the liturgy.
Pre-Cana, here, is different from Wedding planning. The only planning in our prep class locally is the meeting with the priest: he discusses officiant preferences, location (which of the three churches in the parish OR a different church nearby---very common here, despite "rules" for it being a home church---many are too small or have logistic problems, such as a directly adjacent church hall on Saturday afternoons, ruling them out). The couple then, from their choices, is assisted to set a date and location. The FOCCUS is usually administered for a later meeting, and the couple sign up for Engaged Encounter either as a stay-away or locally are referred to those who oversee the program. Pre-Cana, officially, used to meet as groups of couples, but with the introduction of Engaged Encounter, that takes the place as a rule. . .
The priest meets with the couple to discuss the sacrament and review the FOCCUS, and meets to plan separately. Typically priest meets three times with couple to discuss counseling issues and once or twice to plan, or passes that off to a coordinator. It is different if the couple is military or out of the area moving in. . .