Hi Alulette, 

Congrats on your migration from Mailchimp to Klaviyo, and welcome to the community! 

One solution to your problem would be to utliize a custom profile property, such as “First Service Date”, for your existing subscribers. 

1. Create a CSV of existing customers
2. Column A must contain email address (this is Klaviyo’s unique profile identifier)
3. Insert a new column labeled “First Service Date”
4. Paste each customer’s first service date into this column, in the same row as their email address (be sure the dates comply with an accepted Klaviyo date & time stamp format)
5. Import the CSV into your selected list in Klaviyo

More details can be found in this Help Center guide: How to import profile properties using a CSV upload

Then, you can create an automated flow that is triggered by this First Service Date property in each customer’s profile. You can insert various time delays between messages in the flow to deliver on the cadence you prefer. 

More details in this guide: How to create a date property-triggered flow

Please let us know if this solves your problem. Thanks and good luck! 

Thank you very much for your good description. I am trying to create a CSV and add the customers in my flow. It can only go wrong ;-)

I will let you know how it goes

Best Regards Anne

Great! Please do let us know how it goes and if we can help further.