How do employers count "1 year experience"?

From the time I started driving in the company parking lot?

From when I got my permit and started cruising around the block?

When I started driving to and from shippers?

or...

When I got my CDL?

 

When did that happen

 

My hire date and tractor-trailer experience don't exactly line up, though.

I was hired this past April, spent my first week as just a mover riding with other drivers.

Week 2 I was driving Class C straight trucks (had been doing this for four years prior at previous job anyway).

Started driving in the yard later that month.

Got my Class A permit in May.

Started actually driving to and from shippers in August.

Got my Class A license on October 26.

 

All my training has been on-the-job so I don't know if prospective employers count differently than a trucking school does.

 

I mean at a minimum they'll be looking at my CDL issue date, right? Can I use my permit (which I held onto) and let them know I started driving then?