Estimated Tax : First Payment

Say you applied your 2018 refund to 2019 and then made an additional payment (for the 1st quarter) by April 15, 2019.

Since Turbo Tax already knows you applied the refund towards the estimate tax, do you enter only the additional payment on the turbo tax estimated tax section or the total of both amounts?

 

For example,  $1000 refund applied towards next year and an extra $500 by April 15.  When filling out the estimated tax section do I enter $500 ( assuming the program will add in the $1000 refund) or just the $500 payment.  I don't want to take credit twice.