How can I see when the next abandoned cart reminder will be sent to a shopper?

Open Abandoned Carts and go to the Logs tab. It has three views:

• Queue: carts still in the sequence, with Sent so far, Next email and when it's Scheduled.
• Sent: every reminder that went out, with Sent at, Email, Step, Subject and Status.
• Converted: carts that became orders, with the Recovered value and which email Won by.

If nothing is queued, check that each email in the Emails tab is enabled and that capture is switched on in Settings.