Relax! It's a fresh fill, so you're in control. Nobody's dumped any snake oils in it and there can't be any algae yet.
Order a TF100 or K-2006 and your choice of salt test strips.
Then go to the local big box store and pick up a couple jugs of plain unscented bleach, a 4 lb canister of stabilizer (CYA) a jug of acid, and about 200 lbs of salt. Also maybe a simple 2-way test kit. If you buy the 2-way kit, you could order a
TF50 and save a few bucks.
Once the pool is full, add 3 ppm FC using bleach. That's only a quart. Dribble it into the return stream so it mixes and spreads. You can let it mix while you slather the kids with sunscreen. By the time you're done, they can get in. It's the same water they bathe in, right? Note: if the water turns colors as soon as you add bleach, don't panic. It's metals in the well water. It can be dealt with. Just let us know and we can go through that.
Second, add 4 lbs of CYA granules by pouring them in a sock or nylon and hanging it in front of the return jet so it gets pummeled by the water stream. Give it a squeeze every so often and it will dissolve faster.
You can even add the salt now if you want. It's a lot of fun for the kids if you add it and let them play with it. Just inist they keep it in the pool.
Every day add your quart of bleach.
Your test kit will have arrived and then you can test everything. This is when you fine-tune the pH and check that the salt level is good. pH adjustments can be done in a matter of minutes. If you went the simple 2-way kit and the TF50, you can adjust pH sooner. If things are good, you turn on the SWG.
There's more information on what chemical does what and how to add it in
Pool School - Recommended Pool Chemicals
How much to add is explained in
Pool School - PoolMath
... Good luck.
