I have raised E. Tiger Larvae since mid70's and currently have 5 easterns today. Oldest 13 years old.
Once there gills are less than 0.25" long, i place them in a small temporary aquarium with 1" water level. Yes i use white or yellow gravel (only this time in their life) to produce the part on land. The brighter or lighter color helps the sal see the food placed in the aquarium. Rocks are used to build caves for hides on the land part.
I drop small worms in the aquarium or try to hand feed the new sal (this usually does not happen). if the worm falls near the sal and moves around, they will chase the it.
I never had a sal eat any of the gravel !
USUALLY, they will accept worms from the owner within 2 weeks. At that point, i place the sal into the more natuaral setting of Potting soil and Cocnut fiber 1:1 mixture. The first 2-3 years of their life i try to feed them daily (for max. growth) worms, waxworms, crickets....
Enjoy
Hope this helps.