Ready to mail , how long ?

Sorry but Ready to Mail means you have to actually print out your tax return and mail it to the IRS yourself.  So it has not been filed yet.

Or if you did mail it, Turbo Tax will always say Ready to Mail.  Turbo Tax doesn't know if or when you actually mailed it.  And the IRS doesn't tell them when they receivable mailed return.

 You can try to switch to efile     https://ttlc.intuit.com/replies/3985787

The IRS asks that your wait four weeks after mailing your return before using their Where's My Refund? site to track the status of your refund. (They will not send you anything to let you know your refund is on its way.)

Since it has been 6 weeks, should I assume it was not received or rejected?

Call them