Congratulations. Would be great to hear your impressions when you get it as as things break in.
The preamp will take a couple hundred hours to go through its largest part of breakin (~100 - 120 hours SQ can waver substantially)… after that it slowly gets better and better. While ARC said 600 hour for breakin, I actually found it continues beyond that… to about 1,000. I would hurry the first 120 hours… then just use it to achieve the rest of the breakin.
I would recommend waiting on interconnects and cables until all is broken in and you really know the sound. But I think what I say below likely to be a very safe route if you want to get it together more quickly.
When my system got to a very high level of performance like yours, the components have no flaws or nuances you do not want to hear and the best interconnects and cables become those that are as neutral and passed through as much of the signal as possible. To me these are Transparent. ARC and Transparent are a known synegistic combination. I also found their power cords to have a similar impact (don’t ask me why power cords would sound similar to interconnect… I sure have no clue). The only exception for me was the amp power cord. I liked Cardas Clear Beyond for that.