Use of Incense during the Liturgy of the Eucharist
In solemn celebrations, we use incense at two points during the Liturgy of the Eucharist: the Preparation of the Gifts and the Eucharistic Prayer; after the bread and the chalice have been placed upon the altar, to incense the offerings, the cross, and the altar, as well as the priest and the people; at the showing of the host and the chalice after the consecration. (GIRM 276)
The third typical edition of the GIRM simplifies things for us and indicates that the offerings, the cross, the altar, the priest and the people are all incensed with three swings of the thurible. The symbolism of this ritual element is very important: The priest may incense the gifts placed upon the altar and then incense the cross and the altar itself, so as to signify the Church's offering and prayer rising like incense in the sight of God. Next, the priest, because of his sacred ministry, and the people, by reason of their baptismal dignity, may be incensed by the deacon or another minister. (GIRM 75)
During the Sanctus, the concelebrants draw near to the altar and some of the ministers approach it as well, bearing lighted candles and incense. This moment is parallel to the proclamation of the Gospel where lights and fragrant smoke are also used to show reverence to Christ, truly present in the Word as in the Sacrament. The servers should rise with everybody when the people are asked to rise for the Mysterium Fidei; otherwise, they remain kneeling with the rest of the people, and noy remain kneeling until the end of the Eucharistic Prayer. This is in keeping with the basic liturgical principle of uniformity of gesture. It does not make sense, and besides it is ugly, that the servers alone remain kneeling while everybody else are already standing.
Moreover, it does not make sense that they should incense the sacred species, elevated by the priest during the Doxology, found at the end of the Eucharistic Prayer. Not only is this nowhere to be found in the rubrics, it is also incoherent with the solemn liturgical act being done at this moment of the liturgy. This is the point when Christ himself is lifted up as our offering to the Father, and there is no further need for incense while the perfect and definitive sacrifice is being offered. Also, this not a time for adoration but of joining ourselves to the offering of the Paschal Lamb to the Father. (That is why the bread is not 'shown' but 'raised' with the paten.) If there is anything that should rise up with Christ, it is not incense smoke but we ourselves. (Not literally, of course!)
Other things that are too often forgotten regarding incensation are the bows before as well as after incensing a person or object, except at the incensation of the altar and of the gifts when the reverence is made to the Cross or to the Paschal candle at Eastertime instead and the sign of the cross made in silence by the celebrant over the thurible to bless it after having put incense. (GIRM 277)