If you are confident that you are going to receive a refund, then you can file the return when you get the social security number (SSN). There are no late filing penalties when there is a refund because all interest and penalty is based on a tax due amount.
On the other hand, if you aren't sure or you know you will owe a tax due amount you should use "Applied for" in the SSN slot, then print and mail the tax return on or before April 18, 2017, the due date of the return.