I think the stripy one looks old enough for soft food, and if he has
issues with that, we started our bitties on gruel that was part soft
food part water, when they were 4 weeks old (by veterinary advice, the
vets said to give the gruel a shot and the bits were about 3 and a
half weeks old when they first sampled it). By 5 weeks they were on
canned food and starting to munch on dry.
Good luck with your new baby bitties.