Keep it on 24/0, switching to 18/6 is just gonna lower the amount of light the plant is getting, and in this sorta circumstance it isn't gonna benefit too much from it. So stick to 24/7.
The first week or two are the most un-exciting.
You need more light buddy, look for bulbs which have 'Cool white' on them, or something with 'cool' in it. The kelvin rating should be 6500K but if you can't see that on the bulb then just look for the term they use, Warm ..... is usually around 2700K and Cool ..... is usually around 6500K.
Switch over to 6500K and add around 3-4 bulbs, place them around the plant and you'll start to see rapid growth. Water around every 4-5 days, when you feel the top few inches of soil is starting to dry up then water a bit more, but if you water too much, your roots aren't gonna bother so much about looking for water, they'll just think they've already got it and not bother.
Also, temperature, what sort of figures is that hitting?
Anymore advice just drop me a line in a Private message, i miss these from time to time so i might not reply but message me