If your growing from clones and they are rooted, you will want to have those lights about 2 ft at first then if heat isn't an issue then you want to get the lights with in 1 FT from the top of the plants. at a yard away your lumens on a 1K drop down below half and you might as well be using a 400w.
Sunshine is good, I would think about adding some superthrive in the water and after the first week slowly start them up on some nutes, if your going to veg for a short period of time I would hit them with some veg nutes up until the 7'th day of flower and then start your flower nutes. This way they will have enough Nitrogen in the fan leaves to take it all the way threw flower with out starting too much necrosis in the first 2 weeks of flower IMO. Maybe the place you get them from can give you a basic idea of what they have been giving to them or what they recomend as well.
If you just keep the lights under the FT print of the light you really don't have to block off anything.
Adieu