forelight

A forward positioned or forward facing light, especially one used to guide, direct, or navigate; beacon; (by extension) a signal; indicator

Each miracle was a foretoken, and forelight, and firstfruit of the restoration of all creation. When he healed the sick, that cure was a forelight of the sickless state.

[...] but the indications thus outlined of this improvement seem to me but foreshadowings of still better things to come — nay, rather are they forelights — Forelights Of A More Radiant Health That Is To Be.

Light emitted prior to or in anticipation of an event; a previous, former, or early light

The City, it seemed to her, knew it dimly, with a yearning faint as dawn's forelight, which grew stronger with each passing hour, inevitably.

Early in the morning, before the first forelight of dawn had started the birds to prophetic chirpings, the recluse heard light movements in the outer room.