Dependent 17 filed his own tax return before me but not indicating he could be claimed on my return, I have to delete him or amend his return. How long does that take

You will need to mail file your return with him as a dependent.  He will need to amend his return.  This can be accomplished on the TurboTax website if he completed his return with us.  Once he logs into his return page the option to amend is directly beneath his return status.  Once amended he will need to mail in the amendment.