First grow!! / need help diagnosing !! /(PICS)

hey guys.. this is my first grow. I have 2 seedlings, each in a solo cup directly below a work light with a 23W CFL Bulb @5000K. I have 2 fans circulating air, one blowing in and one blowing out, I talk to them daily (they are my babies). I do the hand check for watering purposes daily to make sure they are getting what they need... I think im ok on overwatering but I HAVE A COUPLE QUESTIONS

I was was wondering when I should transfer them to a smaller pot, and any nutes you guys prefer lemme know .

the smaller seedling has a curled down cotyledon with a yellow spot as seen in the pic, and its my first time so I need help diagnosing whats wrong with her and how I can fix her, also the stem is a red/purple color unlike the other which has a green stem (BTW these are 2 different seedlings planted at 2 different times, ironically the bigger one was planted after the smaller one.. the small one is I think really stunted because its like a week and a half old. not exactly sure. but the bigger seedling is only about 8 days old and shes looking healthy and has been growing great the past couple days with Poland spring water and spritzing them every so often if I feel the top layer is completely dry and to help with stem growth and strength.

have these plants on a 20/4 On/Off cycle.

To be honest with you, it doesn't look like a problem at all, Cotyledons usually do that as the seedlings puts on leafs
I do hydro which i find much easier, So I'm not 100% but 80% sure that this is normal plant growth

Your soil appears dusty and dry. How often are you watering?

They look fine, nothing uncommon.

They both look fine, the almost kind of scrunched up one should grow out and be fine. I'd try and get the seedlings up and above the rim of the cup and try and get a small breeze going so they get movement and strengthen up. Good luck man.