The IRS does not permit you to file a return without your W-2 prior to February 15th. However, if by February 15th, you still haven't gotten the W-2, you can file a "substitute W-2"
In this case, you can file using a "substitute W-2" on TurboTax (you can see the link to this on the W-2 interview page), using whatever information you have such as the last pay stub.
Note that on the Substitute W-2, the IRS will ask you what steps you took to get the W-2 (like calling the employer).
Here is more information from the IRS.
[Edited 3/19/2020 1:47 pm CDT - updated link]
