Great!
Get the CYA in there as soon as you can.
Use the sock method to add the CYA.
Once you have the CYA filled sock soaking in the water, consider it as added (even though it won't register on the CYA test for a few days) and dose FC according to the
FC/CYA Levels for CYA 40.
It's safe to swim with FC anywhere between minimum and SLAM level for your CYA.
Continue to add muriatic acid to keep your pH in the 7's. Dose for 7.2-7.4 until your TA drops to about 60. Having a TA around 60 will help slow the pH rise. Once TA is 60-ish, keep the pH 7.6-7.8 or so.