I concur with those who say:
1) No pre-planned Artillery first turn strikes for Defenders or either side in Meeting engagements.
Attackers may (and likely should) have use of pre-planned first turn strikes. WW2 planners did it all the time
Defenders may and should have TRP's, especially for FDF (Final Defensive Fires). Doctrine usually required these be observed positions.
2) No first turn attacks on opponent Set-up Zones. Players should mutually agree on whether and how long to extend that rule for subsequent turns. Size of battle will likely dictate Turn-2 possibly through Turn-5. Default stance should be SZ's are fair game after Turn-1 unless previously agreed to defer a set number of turns.
3) Set-Up Zone may and should be treated as a normal part of battlefield after Turn-1 and before Turn-5.