First, congrats to you and your daughter! That’s quite an accomplishment.
I’m assuming you will already be focused on demonstrating humility, gratitude and gentlemanliness. I would encourage you to channel these same qualities through attire. The basic classics never fail, such as a white or blue or pink oxford cloth button down shirt and tan chinos. You may bring a navy blazer too, but if you determine that’s too formal or warm, it can quickly be removed. Finally, for your footwear — and this is often overlooked – I recommended getting your leather shoes shined.