BigRob welcome, please fill in the signature so we know pool volume pump, filter and SWCG equipment and how your testing the water. I like the TF-100 and also you'll need the Taylor K- 1766 for salinity testing. The simple answer to your question is all chemistry needs to be inline before the salt part of it. Read poolschool for a better understanding.
When you add your salt, make sure the SWG device is turned off for a day or so. You do NOT want a big bolus of salt going thru the plumbing as it can mess up your device's "brain". Mix the salt in for a day and if all gone and dissolved then turn the device on the next day. Use liquid chlorine until then to have your FC at your goal level and then when you turn on your SWG it will only have to work to *maintain* that FC level.