Stretch is very dependent on strain, indicas don't stretch nearly as much as sativas, and to a lesser extent on light spectrum; going from a colder light (high Kelvin number) to warmer light increases stretch. The bigger the change in color temperature, the bigger the stretch.
I was suggesting you start your bloom cycle as I did based on the growth characteristics of your plants, which seem pretty indica dominant to me.
Nonetheless, I think you'll have a good run and it should provide you with plenty of good meds. And of course plenty of fun along the way!