Consciousness starts the moment a mind experiences reality, and a mind experiences reality when it perceives.
In other words, consciousness begins with perception of reality, with sensory experience. The experiencing of the now. And it doesn’t require language, complex thought, or self-awareness. It simply requires a mind capable of experiencing what its senses detect.
This also helps sidestep the pitfalls of talking about souls. Too frequently, debates about consciousness get tangled up with human souls. And that’s really talking about something currently unknown, and perhaps unknowable. To claim consciousness is linked to a soul goes beyond the mind-consciousness question into speculative metaphysics. Once you go there, you must address too many irrelevant things. Things like whether rocks have souls, and whether non-human animals and supernatural beings have souls too. To sidestep this problem, separate the soul question from consciousness itself.
TST uses senses, perception, impressions, and ideas very precisely. Senses detect information, perception is the experience of that information, and ideas form when a mind recognizes or interprets impressions, or connects them. Consciousness begins with perception, not with the formation of complex ideas. Therefore, different kinds of minds have different types of consciousness. Each type experiences reality differently. This includes animal, alien, and artificial minds.