What is more common, to have an outside company conduct your ERM or have it done in-house? We are in the start up phase and I’m the officer but I have little knowledge of this area?

I think the answer is it depends...to really answer the question, you / we would need more info like what your internal resources are, etc.
I would guess that if you are a start-up, that having it done by an outside firm might be the easiest / best way to go.

What are the Officer of?