5.2

im going to do my 1st p.m. soon
should i use 5.2 in my water

You should find out what your water conditions are before thinking about using 5.2 Stabilizer. It does not work as advertised and can add saltiness to your beer.

Run Away!

definitely find out about your water chemistry. My city provides an annual water report, I use that and a spreadsheet to dial up more precise water adjustments.

+1 to the above comments. Your question is kinda like asking if you should add more salt to your mashed potatoes without having tasted them first. Without knowing what you're starting with, there's no way to know if 5.2 will help or hurt your water profile. IMO, if your water does need adjustment it's unlikely that 5.2 is the best thing to add. Unfortunately there's no easy replacement for proper knowledge and manipulation of water chemistry, which can be a complex and daunting exercise. If you can find out what your water profile looks like, we can help you figure out what beers it's good for as is and how to adjust it for other styles.