I wasn't really sure how to use the decal sheets to number my squads and vehicles so I asked around to see how it is suppose to be. The squad numbering work as follows:
Company Command Squad: company number/skull/1
Platoon Command Squad: company number/platoon number/0
Infantry Squad: company number/platoon number/infantry squad number
Veterans : 0/0/veteran squad number
So my army is based on the 3rd company of the 122nd Cadian regiment, simply for the fact that there are more "3"s on the cadian decal sheet. So the squad markings will be like this:
Cadian 122 Regiment
3rd Company
Company Command HQ: 301
1st Platoon
Platoon Command Section: 310
1st Squad: 311
2nd Squad: 312
Veteran Squad : 005
Hope this makes sense!