The IRS requires you to mail Forms 8453, 8949 and your 1099-B if you summarized your transactions in TurboTax.

If your tax return was accepted by the IRS, they will be looking for those forms so you should mail them.

If you want to change any information, amend your return. Your Forms 8949 and 1099-B should have all the dates the IRS needs as long as they were on the 1099-B and accompanying detail. If the dates were missing on the 1099-B that you are sending, amend your return.

Thanks for the reply!!

So the IRS has already accepted my initial tax return. The only amendment I would make is to add the dates that was initially missing. 

Given that they already accepted the return, its probably easier if I just send the 8453 + 8949 from my initial turbotax tax return and add the 1099-B for only the stocks that are missing the date right? Or would I have to include all my 1099-B for all the stocks? (i have different stock accounts thus I have several 1099-B)

Correct. Just send the Forms 8453 and 8949 from my initial TurboTax return and add the 1099-B for the stocks with the missing dates. Your broker would have reported the others. Or you can send everything and let the IRS figure it out.