Yes, your 17 year old can be claimed as your dependent. You say he filed his own return--did he say he could be claimed as a dependent on someone else's return? If he did not say that, your own return is going to be rejected when you try to e-file. If that happens, you have to print, sign, and mail your return--you will not be able to e-file this year.
Your dependent will then have to wait for his return to be processed and then amend to say he can be claimed.
For your dependent--just in case-https://ttlc.intuit.com/questions/3061514-how-do-i-amend-a-2016-return-in-turbotax
Yes, your 17 year old can be claimed as your dependent. You say he filed his own return--did he say he could be claimed as a dependent on someone else's return? If he did not say that, your own return is going to be rejected when you try to e-file. If that happens, you have to print, sign, and mail your return--you will not be able to e-file this year.
Your dependent will then have to wait for his return to be processed and then amend to say he can be claimed.
For your dependent--just in case-https://ttlc.intuit.com/questions/3061514-how-do-i-amend-a-2016-return-in-turbotax