Where/how, specifically, do i enter a schedule k-1 estimate?

If you do not have the K-1 with the partnership EIN, you cannot enter the information into TurboTax.  

Thank you very much for your time and effort in responding to my question, unfortunately, you didn't answer the question at all.

If you have estimated figures to use for the purpose of creating an extension, you enter those figures as if you had a K-1 already. 

If these figures are estimated and used on a 1040 tax return, the fact that they are estimated must be disclosed on the return. 

This is how you would enter these figures:

1. Select Federal.
2. Under  Wages & Income, find S-corps, Partnerships, and Trusts.
3. Expand the section and click Start or Update to the right of Schedule K-1.
4. Select Add or Update the right of the type of K-1 you need.
5. On the next screen, select Edit or the pencil icon to the right of the Schedule K-1 that you need. If it is not entered yet, add the form and enter the information that you can. At this stage it is okay to leave most fields blank.
6. Continue through the section until you get the boxes that you need. Box 1 is for ordinary income or loss. Box 2 is for rental income and 3 is for rental loss. Check the boxes you need and enter the numbers on the next screen. 

Thank you very much JulieS.  This is very helpful information.