Turns out, the 1662 BCP pretty straightforwardly treats the Diaconate as a stepping-stone to the Priesthood.

Here’s one of the Collects from the end of “The Form and Manner of Making of Deacons”:

Almighty God, giver of all good things, who of thy great goodness, hast vouchsafed to accept, and take these thy servants unto the office of Deacons in thy Church; Make them, we beseech thee, O Lord, to be modest, humble, and constant in their ministration; to have a ready will to observe all spiritual discipline: That they having alwayes the testimony, of a good conscience, and continuing ever stable, and strong in thy Son Christ, may so well behave themselves in this inferiour office, that they may be found worthy to be called unto the higher Ministries in thy Church, through the same thy son, our Saviour Jesus Christ; to whom be glory and honour, world without end. Amen.

Then, the final rubric reads:

And heere, it must be declared unto the Deacon, that he must continue in that Office of a Deacon, the space of a whole year, (except for reasonable causes it shall otherwise seem good unto the Bishop) to the intent he may be perfect, and well expert in the things apperteining to the ecclesiastical Administration. In executing whereof, if he be found faithful and dilligent, he may be admitted by his Diocesan to the order of Priesthood, at the times appointed in the Canon; or else on urgent occasion, vpon some other Sunday, or Holy-day in the face of the Church in such manner and form as hereafter followeth.