As discussed in this question, one meaning for じき is "soon, momentarily". Looking it up in my (English/Japanese) dictionary, I found both the kanjis 時期 and 直 for it.
I looked them up further (online), and could only find the meaning of まっすぐであること for 直{じき}. Is my dictionary misleading me?
From just what I've seen, it seems like it's rarely written in kanji, and it makes sense in my head that the kanji for 直{す}ぐ would be used, so this question is more academic than practical, but I'd still appreciate any insight on it.