It will probably inhibit gains a bit, but you probably won't be too amazed with the fat loss. I just did 4 days of 200mg (powder) before going to 400mg. I started seeing the real effects at 400, and I'm going to 600 soon. Maybe my shit is underdosed, but i felt almost nothing on 200mg a day. A little heat after eating carbs, but I was very comfortable on it, with no trouble sleeping. 400mg a day and I would breathe heavily after moderate activity, even just going up stairs and i noticed i was breathing harder. I was pretty comfortable on 400mg for the most part too, except I did get pretty mean heat at night, so I needed some melatonin and benadryl to sleep.
Keep in mind my shit may have been underdosed. I'm not a very big guy (180lbs), and I've heard many guys bigger than me really feeling the effects. I've never used t3, but I'd like to try it out to compare the two drugs.
If you really think you need it, I would do it 7 days instead of 5, and maybe increase to 400mg for the final 3-4 days. If you're running var as a cutting cycle then this will help you cut, but if you probably won't see gains during that week of DNP.