When I started my SWG, I did not have a test kit. I went by the unit display for salt. CYA I did use a test kit.

Given that you have fresh water in the pool, it probably does not have much salt to begin with. What is the salt operating range for your SWG?

Most SWGs have dosing charts in the manual to get to the correct salt and CYA levels. Follow those but target the low end of each to start with so you don't overshoot.

For 2800 ppm, you will need about 430 lbs of salt for 18000 gallons. After a few days you can always add more if needed. The unit should tell you if you need more but you can always run it low until your test kit comes.

Also, you will need CYA. Target 60 ppm initially which is about 9 lbs. Again, you can always add more if needed.