It wouldn't hurt to add stabilizer from the start--follow label directions and add enough to tet to about 20 ppm based on your gallonage, for starters. Remember that it takes a very long time to dissolve, so don't backwash or retest for a week or so. In the meantime, you can go ahead and bring your Cl up to 2-3 ppm, but you're going to have to add it daily to make it hold until your stabilizer levels start coming up.

What impact pucks would have on your pool depends a lot on your fill water. They tend to be very acidic, so if you have a constant problem with pH rising, they can be helpful in keeping it down. They will not affect your alkalinity. However, they do tend to add quite a lot of CYA over time. You can start very low with your CYA levels, then use the pucks until the CYA gets to where you want it, if it doesn't cause problems with your pH.

I wouldn't shock the pool until you know for sure the metal content--if you nave no metals in the original water, then it wouldn't hurt to shock it to 12-15 ppm, then let it drift back down to the 3 range.

Janet