Tertullian believed God always had his Reason or his Word AND that God was alone before he brought his Son into existence. He said both things and clearly believed both. It’s only if you impose a strict idea that Word=Son that there is a problem and you have to negate one or the other of Tertullian’s statements. Tertullian made a distinction between God’s Reason which he always had, and his Son which he brought into existence and thereby became a Father. Tertullian did believe that Jesus is divine in some sense, just as JWs do, even God from God, if you like. This sits alongside his view that there was a time when the Son didn’t exist and that the Son is distinct from God and subordinate to him. Tertullian is eminently clear on these points:
I am, moreover, obliged to say this, when (extolling the Monarchy at the expense of the Economy) they contend for the identity of the Father and Son and Spirit, that it is not by way of diversity that the Son differs from the Father, but by distribution: it is not by division that He is different, but by distinction; because the Father is not the same as the Son, since they differ one from the other in the mode of their being. For the Father is the entire substance, but the Son is a derivation and portion of the whole, as He Himself acknowledges: My Father is greater than I. Against Praxeas 14