Hi Anuj,
I had applied in R1. After submitting my app, I got an email with the application next steps. The first point was as below.
"1. Log into your GIAC MyStatus Page to pay your application fee.
1-2 business days after application submission, your application will load with the Graduate and International Admissions Center (GIAC) and your invoice will be available. If you qualify for a fee waiver, do NOT pay the application fee. Your waiver will be processed in 7-10 business days. Once paid, application fees cannot be refunded."
If you're making the payment within 1-2 days of the deadline, that's fine, I guess. But it would still be safe to await confirmation from Adcom. Better you give them a call.
Posted from my mobile device