The AD9653 data sheet provides the functionality of SYNC

When I want to use the functionality of sync next only,how do I configure this register?2'b10 or 2'b11? expecting a reply,thanks.
AD9653
Recommended for New Designs
The AD9653 is a quad, 16-bit, 125 MSPS analog-to-digital converter
(ADC) with an on-chip sample-and-hold circuit
designed for low cost, low power, small...
Datasheet
AD9653 on Analog.com
The AD9653 data sheet provides the functionality of SYNC

When I want to use the functionality of sync next only,how do I configure this register?2'b10 or 2'b11? expecting a reply,thanks.