It is easy to do it either way.
I do want to caution you however, that IRS does charge a fee (can be waived depending on income level) for a payment plan, also interest and failure to pay penalty, so any amounts you can pay by the due date (April 17, 2018) will reduce some of the costs.
Please see below for details:
https://ttlc.intuit.com/replies/4678634
