Word which means "in its early stages but important"

The words that come to my mind are nascent and infancy.

nascent (adjective)

definition: just coming into existence and beginning to display signs of future potential.

Usage:

The nascent stages of Andy's career proved to be challenging, yet he came out with flying colors

infancy (noun)

definition: the early stage in the development or growth of something

Usage:

The well established company has nurtured "Speak Up" culture right from its infancy.

I wanted to post this as a comment but I don't have enough reputation to do that. So posting it as as answer.

Edit: : Edited answer, added definition and usage to be in line with the answer style guidelines of this community

It may have been 'seminal'

Seminal - adjective

4 - highly original and influencing the development of future events: a seminal artist; seminal ideas.

www.dictionary.com

Or perhaps it was 'groundbreaking'

Groundbreaking - adjective

3 - originating or pioneering a new endeavor, field of inquiry, or the like: Pasteur's groundbreaking work in bacteriology.

www.dictionary.com

Incipient- something is in an early stage of existence. "In its incipient form, basketball was played with a soccer ball and peach baskets for goals. Bouncy orange balls and nets came later."