Firstly, congratulations on ordering the RS3, I've postponed my decision for financial reasons but cannot find a competitor I'm content with, so RS3 will happen (hopefully next year!).
Secondly, I'll caveat this (rather obviously) with the statement that it is all just my humble opinion; thankfully we are all different and our opinions vary accordingly!
Having seen and driven the Rs3 in Daytona grey several times, I cannot help but feel the colour does not do the marque justice. I wouldn't hesitate to have Daytona grey on a multitude of other Audi models, but for me, on the RS3 it just looks too sober.
It's a very popular colour (dubbed accountant grey in various threads on this forum) but for me, I wouldn't want this car to blend in quite so much in colour, as well as the already subtle styling for an RS model.
The black pack you've specced is a must (again imho) as the silver pack increasingly makes the car look more ordinary when matched with Daytona grey.
I hope this helps, and ultimately all that matters is that the car and spec are right for you, not anyone else!! Enjoy, and I hope the wait isn't too long!
R&G