You can file without the 1099 and then the IRS will notify you of the unreported 1099 and compute your correct taxes. If the employer has created the 1099 and sent it to the IRS.
If that has not happened, then you can file now and amend when the 1099 is received and after your return has been processed.
If you are going to receive a refund, then you do not have to file until you receive the 1099.
