I use a TDS meter & almost always slow acclimate fish over at least an hour. My water is usually much lower TDS than others. If it's a huge difference, I also raise the TDS of my QT to closer match the bag. As Bob pointed out a few hours won't prevent osmotic shock if there's a big difference. I guess, with no real knowledge, a difference of ~200ppm, I drip: more, I alter the QT params too.
People & lfs that use salt are are a real PITA as it adds a lot of TDS but it's not something I test for like GH & KH or use much of to raise QT TDS unless I ask if salt has been used. I also slowly remove salt if I've used it as a medication over a period of a couple weeks, just as I slowly lower TDS in QT if I needed to raise it.
I too add a drop of Prime to neutralize any ammonia.
For moving fish or inverts tank to tank, plop 'em in unless there's some major difference in TDS. Lower to higher TDS is less of a problem for fish than higher to lower.