I first ensure salinity is matched QT to DT. I then scoop some QT water into a jug, put the fish in that, dry the outside of the jug and hang the jug in the DT to match temp (jug has a flat handle so I can hang it over the side). I do a short drip acclimate (15 mins or so) with DT water to allow for other parameters being different (about the same amount of DT water as the QT water in the jug), then put a net into a bowl, pour the fish into the net and bowl. Then take the net out and quickly transfer the fish to the DT.
A little QT water will transfer with them but very minimal - my DT is 244L and I’m guessing less than 1 mL will transfer, which is .004% of the DT volume. I’m not really worried about that amount of QT water. So far this process has worked very well for me.
I’m an 18 month old newbie however so bear that in mind!