When should one start doing this though, in a companies life cycle?

What is the most reasonable point that meets the criteria of 'as soon as possible'?

Because I imagine out of the gate doing this could be a net negative, not a net positive.

On the other hand, I'm not sufficiently well versed enough on the absolute latest devops techniques that may make this whole thing trivial, but I thought all the major cloud providers had just enough quirks in their Terraform support you can't write once standup / deploy anywhere