Autoflower under T5

So I am starting off a small grow under a few 4 inch - T5 lights with grow bulbs in them. Most of the strains I am growing are autoflowers, which I hear should go on a 20/4 light cycle or some variant of that.

I know T5's are not the best to use and lower yield but its what I got to work with. What I am trying to figure out is with autoflowering strains should I grow with grow (6500k) blubs from the seed then change out to a flowering bulb (2700k)? What is the time you would usually change bulbs to flowering bulbs? Since technically the autoflower strains will always flower. Just don't know what works best.

A 4 inch T5 is not going to produce much light - did you mean 4 foot?

I use T5s to start all my autos....at 24/0 ....which I continue until they show sex and worthy to be moved to my hps system.....my bulbs are 5500k ....so no input on any change....They'll produce smaller buds, but if you control the other important factors such as temp, ventilation, humidity...you'll be fine.....get those lights no more than one inch away if temp isn't a prob....good karma to ya grow.

Any chance you could show us a pic of this magical 4" long T5? But in all seriousness a 4' T5 fixture could get you through flowering but I'd recommend some sort of training (LST or SCROG) to keep the plants low and make up for the poor penetration of the lights.