According to the GIRM the announcements should come after the prayer after communion.
#89 talks about the prayer after communion:
- To bring to completion the prayer of the People of God, and also to conclude the entire Communion Rite, the priest says the Prayer after Communion, in which he prays for the fruits of the mystery just celebrated.
In the Mass only one prayer after Communion is said, which ends with a shorter conclusion; that is,
Code:
* If the prayer is directed to the Father: Per Christum Dominum nostrum (Through Christ our Lord);
* If it is directed to the Father, but the Son is mentioned at the end: Qui vivit et regnat in saecula saeculorum (Who lives and reigns forever and ever);
* If it is directed to the Son: Qui vivis et regnas in saecula saeculorum (You live and reign forever and ever).
The people make the prayer their own by the acclamation, Amen.
Then come the concluding rites:
D. The Concluding Rites
- The concluding rites consist of
- Brief announcements, if they are necessary;
- The priest’s greeting and blessing, which on certain days and occasions is enriched and expressed in the prayer over the People or another more solemn formula;
- The dismissal of the people by the deacon or the priest, so that each may go out to do good works, praising and blessing God;
- The kissing of the altar by the priest and the deacon, followed by a profound bow to the altar by the priest, the deacon, and the other ministers. Source]