Not to preach, but pool stores are not always accurate in there reading. I took the same sample to 3 stores the same day and got different reading from all of them and from testing myself. The time it takes to drive to the pool store you could have tested already. If you want to continue to use a pool store, please double check by testing yourself or with other stores to see if they are providing accurate results.
You can open either way. I would get everything installed and not use the SWG to start. Get the pool running and the water clear and chemistry in check. Then check the salt level and start adding salt to get to the level your SWG requires. Don't add all at once. I add 50% of what I think I need and check the salt level to see if its gone up half way to where it needs to be. I then add 80-90% of what is recommended and recheck. If you start early you can do it in a day, or you can stretch it over a few days. At this point you should be at the lower end of the salt range and can add a bag or two or three to get to the ideal level. For me the SWG and my testing don't match, I try to keep the middle of the range based on the what the SWG reads, but will skew it higher or lower depending on what the Taylor kit result are.
At this point start using the SWG for chlorine and figure out what amount of time it needs to run. Take a few days of trial and error and I will add LC if need to keep the FC in the safe range.
