Handbook of Liturgical Practice of the Russian Church Abroad
Following the conclusion of the Entrance Prayers and the entry of the clergy into the Holy Altar, they proceed from the veneration of the Holy Table immediately to their vesting. We must always remind ourselves that the donning of vestments for the Divine Service is itself a sacred act, liturgical in nature. There are prescribed prayers appointed for each vestment, which is itself blessed prior to being put on, and the prayer said during. This must be done reverently and piously, without idle conversation taking place between clergy or servers during this time. The prayers should be said carefully and deliberately; if not known from memory, the Service Book should be open so that they can be read verbatim by the Priest as he vests himself.
In parishes with well trained and diligent Altar servers, they will assist the Priest in his vesting by ensuring that his vestments are already prepared before he needs them (i.e. set out and readied), and then handing them to him, piece by piece, silently, as he says his prayers and vests himself. This requires the server knowing the proper order that the vestments should be handed to the Priest, so that he may be a help rather than a distraction; but servers that take the effort to learn this and assist in such a manner, make a great offering of piety and help to the Priest as he prepares for his ministerial work.
Questions should not be asked of the Priest by servers during the vesting, nor should the priest permit himself to be distracted by other tasks in the Altar at this time. We vest fully, first, with all our prayers; then our hands are washed; and only then do we go about the various works of the Altar and any minimal conversations or questions that may need to be discussed prior to the service.