When does a Taunt action take effect during starship combat?

According to Starfinder’s starship combat rules on the Captain’s Taunt action:

You can use the communications system to broadcast a taunting message to the enemy vessel. You select an enemy vessel and a phase of combat (engineering, helm, or gunnery), and then attempt a Bluff or Intimidate check (DC = 15 + 1-1/2 × the enemy starship’s tier). If you are successful, each enemy character acting during the selected phase takes a –2 penalty to all checks for 1d4 rounds; the penalty increases to –4 if the enemy’s check is made as part of a push action. Once used against an enemy starship, regardless of the outcome, taunt can’t be used against that starship again during the same combat.

My question is when do these penalties take effect?

Example of why this is unclear: In round 1’s helm phase, on behalf of an NPC crew, the GM rolls for the piloting check, a piloting stunt, and a science officer action. Then, after these rolls have been made but during the same helm phase, the player Captaining the PC ship successfully Taunts the NPC ship and rolls a 3 for rounds of effect.

Does the -2 penalty apply retroactively to the GM’s die rolls in round 1 and then continue for rounds 2 and 3? Does the penalty last until round 3, but the NPC crew escaped the effects for round 1 because the GM rolled before the player? Or does the -2 penalty kick in at the beginning of round 2 and last until round 4, guaranteeing the NPCs suffer three rounds of effects even though they avoided the penalty in round 1?