So i know my plants aren't getting enough light, my question is, does it make a difference if I turn on the light as soon as the direct sunlight goes away or if I do it when I get back from work (and the sun has been gone for a while)
It's better to try and mimic nature where there is a continuous period of light followed by darkness. Some plants need a period of darkness like tomatoes and many flowering plants but other tropical plants are just fine with getting light twenty four hours a day.
This photo, courtesy of @geermc4 shows what happens to tomatoes with different light periods
I use a timer to extend the daylight period. Given the low cost of one it's probably the easiest solution.