sure go ahead and fill it, either way is fine.
Ive seen those plants packed in the gel medium, same stuff you get at wal mart as soil-less plant watering stuff...but, what matters is how the grow warehouse made the plants, emersed or submersed before packing. Either way the plants will adjust, it just might take 3 months before you can tell.
There is literally nothing you can do to kill the plants on the way to work outside of harsh biocidal activity, and you dont strike me as the angry biocidal type
worst you can do is stress em, theyll send out new leaves when happy, relying on the nutrient stores in those corms or roots until the time is right.
Enjoy! I couldn't tell if you have fish in there or not. If not, the plants will appreciate 1 drop of any liquid plant fertilizer meant for aquarium use every month or so, it appears you have slow growing type plants
make no judgments off the leaves you have, thats good advice. They have to die likely to make way for the correct ones in the water level you choose. But when new shoots come up, watch them for coloration and longevity...thats the real ticket.
yellowing or darkening at the ends is most likely just a need for fertilizer occasionally, iron or magnesium chlorosis.