T5 lighting schedule -- suggestions please


I just received my sunlight T5 retro for my 75g. I have 3- 2 bulb units. The bulbs that i am starting out with are 3-12K, 1 purple and 2 actinic. I am thinking i will have my 2 actinics come on first then an hour or so later the purple and one 12 K then the last 2 12K for a shorter photo period. I have yet to mount them on the tank so i am not sure if i am going to like the coloring of the tank. I only have a few corals at this time - a few shrooms and a few zooz and green star polyps. I am looking to get into some SPS and LPS. and possibly a clam down the road.
I am not quite sure of the placement just yet in the tank, but i am thinking of going with:
Front to Back -- 2 actinic, 1 12K, 1 purple and 2 12K. -- or should the 12K go in the middle? Does the exact placement make that big a difference? or is that really dependent upon the placement of my corals/clams.