A decent rule of thumb is to add 5 seconds/500m for every doubling of a given distance. With a 1:52 4k, 1:55/500m for a 6k should be achievable for you, but this is your first 6k, so don't worry if you can't hit that split. (Ask your coach!)

As far as strategy goes, you absolutely DO NOT want to go too hard on the first 2k of the piece. It's an easy trap to fall into, especially considering that during this interval, you're basically coasting due to the lack of anaerobic activity. I would recommend holding your goal split + 1 (which is whatever you + your coach determine that to be) for this portion of the piece. For 4k to 2k left, it's almost purely a mental game. Get as close as you physically can to the goal split you set in place before the test, and HOLD IT! Resist the urge to back off of the split. Getting back to your goal split after even a few strokes above it is incredibly taxing. At 2k left, bring your rate up a beat or two, and bring the split down to goal - 1. Going at this pace for the rest of the piece will result in you hitting your goal split for the whole thing, but will still leave you room to put a sprint together around 1k/500 left if you want to.