In need of 12/12?

Expect 2-3x growth and make sure to flip before you can't fit another ~4 weeks or more of solid vege growth after flip. have you filled roughly 1/2 the area? 70% of length and width is 49%

lot of space between the nodes, might have needed to move the light closer earlier or its intensity increased. eg if dim was at 40% to increase it to 60% You don't have a diary linked, so no idea what the whole plant looks like or what it is. Auto/Photo/Fast or anything else about it. Autos will flower on their own, photos and fast flowers will need to have a change in their light cycle aka "photoperopd Needs a bit more information. You can flip to 12/12 when its mature and if it a photoperiod plant, if its an auto keep it at the longer lightscheude. If you shorten it, make sure you increase your lights intensity to creat the same DLI. DLI is metric used to calculate the amount of light with its density received in a 24hr period. So A DLI of 30 can be achieved over 18hrs or even 12hrs depending on the lights intensity. wikipedea has a nice article on it.

If it were mine , I would top down the 3-5 pairs and attempt to spread her out for a week. Then flip. I dunno from the pics she looks kind of lanky. As your first one it's hard to slow down and dissipate the pressure to get to the finish. Take your time in veg shape you future. Learning is fun. On a side note, if you only get it 80% right, you'll still have something to show at the end. Every leaf is not sacred.