It sounds similar to what I did when I started my plaster pool. I was debating about doing an acid start or a chlorine start for the plaster.

A chlorine start is a basic balance of the water after fill and is very low risk. The downside is that you have to deal with the plaster dust. Most plaster pools are started this way.

An acid start drops the Alk to 0 for about three days and basically dissolves all of the calcium dust in the pool. It is pretty risky unless you know what you are doing. It is pretty easy to get it wrong and damage the plaster. As you bring the PH up, some of the calcium drops out of solution but it is slow enough that the filter can catch most of it. However, I believe that a true acid start would have required more acid than what your PB put in.

I chose a middle ground and droped the PH down to about 6.8 for about a week which limited the dust somewhat but I did not need to worry about scaling or damaging the surface. It sounds as though this is what your PB may be aiming for or something slightly more aggressive. After a few days, I would check it to make sure the PH is rising and is at least about 6.8.