Maxium Negative or Positive Depth allowed?

Hi

I’m building a side scrolling battle game like Warfare 1944 but to add uncessarily complexity its going have an isometric front.

So my question is… I need to add units and have them progressivly go down 1 depth each unit added. I just want to make sure it doesn’t go beyond the maximum negative which is restricted.

So should I just start with the highest depth then work down and be safe?

Thanks