Can you script the order of attacks (setup turn 1, burst turn 2) in Dragonfire?

No. It's a false assumption: you don't play a combo in Dragonfire, you compose it.

Once the fight starts, you control nothing:

• The within-round action order is set by Initiative, not by you.
• "Rounds 2/5/8" or "3/6/9" procs are locked to the global round counter, not to "when the dragon decides".
• The damage type (physical/fire/tactical) is automatic, based on the dragon's abilities — you don't pick it.
• The alternation between basic attack and Order is automatic.

So "set up on turn 1, trigger the burst on turn 2" is impossible: the machine runs itself. Your only real choice is beforehand: which 3 dragons you gather, in which positions (Center/flanks), with which troop type.

Your lever is composition: put the Panic applier together with the dragons that cash in, and let Initiative do its job. Combos are prepared at the castle, not during the fight.