Winback campaigns can work really well to get lapsed or defected customers to come back and buy again.
Timing-wise you need to be careful though. Since winbacks typically include an incentive, sending them too early you risk giving away the incentive to customers who would buy anyway. Send them too late and the winback won't be as effective.
If you're measuring your Customer Purchase Latency, like with Repeat Customer Insights, then you can use that to get a good idea of when to send the winbacks.
CPL measures the number of days in-between regular orders. Since winback campaigns are sent to irregular customers, you'll want to send them at some multiple of your CPL. Twice the CPL or one year is a good rule of thumb (pick the smaller).
For example, if your CPL is 35 days then start sending a winback campaign after 70 days with no order. If your CPL if 160 days, then start at 320 days. If your CPL is 14 months, then an annual winback might work (though I'd reduced the incentive level to be as low-cost as possible to prevent too much cannibalization).
My app has suggestions like this in the Focus reports. They each focus on a different aspect of your store and consolidate different metrics and analysis into a single topic. With the recently released automatic email sending you can get those in your inbox every month or every week.
Eric Davis
Measure which customers you're retaining and which you're losing
In order to keep your best customers, you need visibility into what's going on with them. Repeat Customer Insights will help you track down where you're losing customers and how to better target new ones.