If you mailed your return, the status will always be "ready to mail." TurboTax has no way of knowing if you actually dropped the return in the mailbox.
For the future, one suggestion to give you peace of mind to know your mailed return was received is to send it by certified mail with a receipt returned to you.
You can track your Illinois tax refund, please see FAQ below for instructions.
https://ttlc.intuit.com/replies/4779653