How often to feed young sallies

I'm wondering if anyone can give me some advice on how often we should be getting young spotted salamanders? They morphed in June and we've kept a total of 6; 3 "younger" and 3 "older", separated into two large tupperware-type containers with holes drilled in the lids. Instead of soil we're still keeping them on several layers of brown unbleached paper towels (can recommend this housing enough! So easy to clean!). Currently we're feeding them earthworms from our garden, cut into roughly 2 inch pieces (they're still good and active this way, the Sals seem to like the hunt). They're sprayed down nightly with pond water.

We're just wondering if maybe we should cut down to every other day feeding them, or even less? Should we vary their diet somewhat? I know earthworms are a complete diet, but it seems a tad... Boring lol.

Also... We have a 29 gal tank ready to go... Any thoughts when they should go into that instead of their containers? We found that the feeding didn't go too well when they were tiny in the soil. Now the largest is about 3.5 inches.

I'll post a few pics... They're gorgeous!
Thanks in advance!

that one looks like you could just feed it once or twice a week...and smaller portions

Curious... Do you mean that she's a fatty... Or in general young salamanders only eat once or twice a week? I can't seem to find information on that. Thanks.