Install Lacerte 2018

From Lacerte 2017, proforma the clients you want to 2018.

From Lacerte 2018 enter estimated income & deductions to a client and confirm estimated payments. Create a column in the Client Screen for something like TOTAL TAX and TOTAL PAYMENTS. I don't think that will pick up the 2017 payments, but that might be what you have input for the 2018 estimation.