I submitted a payment plan for what I owe on federal, and provided my checking account # and routing # for automatic debit, do I need to send a live check for the first?

[TomK]

Instructions for Form 9465 (Rev. December 2018) Installment Agreement Request just state:

"You can choose the day of each month your payment is due. This can be on or after the 1st of the month, but no later than the 28th of the month. 

When we approve your request, we will tell you the month and day that your first payment is due. 

If we haven’t replied by the date you chose for your first payment, you can send the first payment to the Internal Revenue Service Center at the address shown earlier that applies to you."

Thus, you can mail a check if you prefer.  Please see screenshots below.

For more information: https://www.irs.gov/pub/irs-pdf/i9465.pdf