12/12 ?

you call. if you need to push them into flower.if not i;d veg em out a bit longer.

When you have filled rouglhy half the area that your lights can cover properly with 12 hours of operation, flip to flower. there are so many variables invovled.. it's hard to give more than a generalization. If you are experiencing slow growth, may want a bit longer. Those are fairly small for 38 days. Your VPD, lack of aeration in substrate (use more perlite or similar next time for sure) or other variables may not be allowing the best growth rate. Strongly suggest you get comfortable with potting up so you don't have tiny plants in large pots.. that slows things down too.

Wait some days more.

Its down to you really in theory you can go 12/12 from Seed but if I was growing those I would wait until there bigger and healthier.. patience is key...