Those are definitely stretched and you'll only be able to bury an 1-1.5" on transplant -- too much deeper and you really increase chance you rot the stem.
Stretch = crank up light more. too tight = reduce light a bit. Observe and adjust. take some notes of timing and such and you can have a solid plan that preempts any visible issue.
So, 24h is fine initially, but the moment you see those things getting lanky you need to start cranking up that light. Observe and adjust. White stem is a sure since of stretch, and you can definitely identify it long before this point. It may not be able to take full power of light (35-40 dli in ambient conditions), so there will be 1 or 2 steps between. How it grows is the guide. The plant dictates everything, just learn to read it.
DLI is what matters not hours of light, though that is a factor in the equation for DLI. you can give fewer hours of light but still give more photons per day than 24/0. Readup on DLI to get the gist of it. it's a way of speaking about light intensity that translates regardless of the size of your garden or hours of operation. Simply how many photons per day per standardized area. (daily light integral = DLI)