It can’t all be consecrated while it is in a pitcher, for the rubrics specify that at the beginning of the Liturgy of the Eucharist, “”the deacon (or the priest) pours wine and a little water into the chalice…”” Except for the wine in the chalice, any additional wine is supposed to be consecrated in flagons or pitchers.
The document that deals with this question for dioceses in the United States is called This Holy and Living Sacrifice (HLS). It was written by the U.S. bishops and was approved by the Holy See in 1984.
The document states that before Mass,
the wine should be placed in flagons or pitchers of careful design and quality as befits the celebration of the Eucharistic mystery…The vessels should be sturdy, made of materials which are solid and nonabsorbent. Preference is always to be given to materials that do not break easily or become unusable. Before being used, vessels for the celebration must be blessed by the bishop or priest according to the Rite of Blessing of a Chalice and Paten. (HLS 40)
During Mass itself, the wine may be consecrated while it is in the flagons or pitchers. It is then poured into chalices during the fraction rite:
When the altar is prepared after the general intercessions, the wine may be brought forward in one chalice or, when the assembly is very large, one chalice and as many flagons as are necessary. Only one chalice (and the requisite number of flagons) and one large paten, ciborium, or similar vessel should be on the altar during the rites of preparation up to and including the rite of the fraction, when other empty chalices and ciboria may be brought up to the altar. At that time the consecrated bread is placed in several ciboria and the consecrated wine is poured into enough chalices for use in the Rite of Communion. (HLS 42)