There is one thing better than being underdressed AND better than being overdressded... to dress appropriately, according to what you have been told and the stage you are at (in stage 1 you are just a number).
Based on that, my advice is forget the suit for stage 1!
I wore trousers (not jeans) and a shirt for my stage 1 and that was more than enough. In fact, I wore a suit wihout tie in my stage 2. Only for stage 3 did I wear a tie.