To check if you've successfully initiated a payment, go to the 'Pay' screen from the main menu. If a transaction has been processed successfully, it will display immediately under the ‘Paid’ tab in the web portal, or 'Scheduled' if you've set it for a future date.
It takes 2 business days for a payment to be disbursed to the supplier and on the day it's paid out it's usually circa 2-3pm that it will reach the supplier's bank account. When the payment is sent to the supplier you will receive email confirmation.
You can also click into a payment under the 'paid' tab to check that it's been marked as 'disbursed'.