I would complete the repetitions of doing the shoot once - clean back to bare steel bore until the bore substantially stops copper fouling. For quality barrels, this is often 10 shots or less. After these initial bore break-in shots have lapped any roughness out of the new bore, I would then apply the Gun Juice using the latest heat gun application method.
So break the bore in bare-back, so to speak. Nothing but bullet jacket running in direct contact with a squeaky clean bore (no Gun Juice applied). After the clean - shoot once - clean - shoot once - clean... process largely eliminates the copper fouling experienced during the first few bullets fired, THEN treat with Gun Juice
That's how I do it. I don't want the Gun Juice in the bore interfering with the lapping of the new bore during the break-in process.