Max, your thoughts are good, and you need to mention the FC in the tap water. It's also fair to mention the amount of error with a 3:1 dilution. Agreed it's little compared to the level of FC. To OP, if you do this, be careful measuring water, and test your tap water (could be anywhere from about 0.7 to 4 ppm FC). I agree it would save on titrating reagent.
An accepted method is to use a 5 ml pool water sample, and then 1 drop = 1 ppm FC and a 5 ml pipette is the best thing to have for this. (pharmacy or pet store). When you get to the OCLT, you have to use the 10 ml sample, but prior to that, these are techniques to save on reagent, so you won't run out in the middle of it.
Perfect option is to order a 2 oz bottle of R-0871 FAS Titrating Reagent, and not worry about running out.
Glad you're underway with the SLAM. MMMaintain many times the first day, and 4 times a day after; the more often, the quicker the SLAM.
Brush often and seek out algae hiding places and make sure they get scrubbed and soaked in pool water or stronger.