Your first credit card payment will be due within 25 - 30 days of your statement closing date. Each card has a different closing date so check your Cardholder Agreement for specifics. As long as your payment (which is at least the minimum amount due) is received on or before your payment date, your account will be in good standing.
If you need to wait until the actual payment deadline date, check your Cardholder Agreement to see what the cutoff is for the day so that you ensure you’re on time. Some accounts will have until 8 PM that day, while others may be earlier.