Good choice on ignoring the recommendation for FlocThey recommended BioGuard's Power Flock, but it's raining so I had an excuse not to buy. She said not to add stabilizer until clear because of all the vacuuming and backwashing, but with CYA only being 13, don't I need it up first to help retain Chlorine?
Wait until you get your test kit and you test the water, but yes you will probably want the CYA up around 30 for the SLAM. From the SLAM guidelines:
SLAMing an outdoor pool is most effective when CYA is around 30 to 40. Below 30 you lose too much chlorine to sunlight. As CYA goes up, SLAMing requires more and more chlorine, which starts to get impractical around 80 or 90. With CYA above 90 we recommend replacing water to get CYA down before you start the SLAM process.