One question I get frequently from Repeat Customer Insights customers is, when should I contact customers?
The simple answer is: frequently and as soon as possible.
But that's not useful is it?
Based on the data I've seen, the biggest gap Shopify stores have with repeat customers is getting a new customer to come back and make a second purchase.
How well you bridge that gap sets the tone for the entire customer's lifecycle (and thus, their Lifetime Value).
I'm a big supporter of email and emailing often so I recommend starting to email as soon as possible. Start with their order confirmation, shipping updates, and delivery confirmation.
But also start to email them to introduce them to your brand, products, and everything you stand for. Tell stories about customers or yourself as much as possible, they're easier to understand and don't come across as salesy.
Eventually you can start to sell your products harder.
The optimal time would be a bit before the average time of your second orders. So if you're getting second orders 25 days after the first order, start selling around 20-24 days.
Don't know the average time of your second orders?
Repeat Customer Insights's Customer Purchase Latency report will tell you that for various time periods (this year, last year, all-time, etc). It also has a dozen other customer behavior metrics that you can use to custom-tailor your email timing to.