Sign of the cross

"At every forward step and movement, at every going in and out, when we put on our clothes and shoes, when we bathe, when we sit at table, when we light the lamps, on couch, on seat, in all the ordinary actions of daily life, we trace upon the forehead the sign."

"Ad omnem progressum atque promotum, ad omnem aditum et exitum, ad vestitum et calciatum, ad lavacra, ad mensas, ad lumina, ad cubilia, ad sedilia, quacumque nos conversatio exercet, frontem signaculo terimus." 

     Tertullian, De corona 3 (AD 211), trans. Thelwall (ANL 11/ANF 3).  Tertullian, writing in his (final) Montanist period, here cites Christian tradition on the signaculo (sign of the cross) in support of the Christian tradition against wearing "a crown upon [the] head, except at a time of trial" (i.e. military service:  "not one of the Faithful has ever").  If the latter must be abandoned, then so should the former (and all other such "mere" traditions); if the latter abstention, then the former practice, too.  Trans. Conacher in his 2020 translation of the article on "La signation dans l’église des premiers siècles" by Cyrille Vogel (La maison-dieu no. 75 (1963):  37-51):

"Every time we go out or go anywhere, before and after all our activities, when we dress and put on our shoes, when we wash, at table, when we light the lamps, when we go to bed, when we sit down, whatever we are doing, we trace the sign of the cross on our foreheads."

According to Vogel, if we are willing to cite the gnostics (as we should be, for there is nothing uniquely gnostic--or for that matter Montanist, or even pagan--about the signatio), testimony to the custom can be pushed back fifty years behind 211 (Vogel 38n6 on Montanism; 41-42, incl. 42n19, on Gnosticism; and 44 (i.e. sec. 2) on paganism).