'to get in on the ground'

Hello,
This is my first time here.
I am needing help to find out whether this expression means to be one of the first?
Anyone could tell me?
Thank you
Marcia

It means exactly that, perhaps derived from being part of building something from the very start, such as a house.

More often, get in on/at the ground floor. I think it refers to getting into a lift/elevator in a building. It means to be there at the beginning of an enterprise. It's often used about investments which have risen sharply.