How long do I have before I need to setup a tank for the froglets when they climb out?

Some of the tads are developing faster than others. Some don't have hind legs. What should I do in this situation?

Is it okay if I transfer the further along tads in a separate shallow dish with the same water and put that dish in their temporary tank while they climb out?

This temporary tank will be their tank while they absorb their tails and learn to eat pinheads. What should this tank consist of in terms of substrate, decor, water supply etc.