Conditional statement for hour of add to cart event tracking

Hi @Piotr,

If you want, it could be easier to schedule your emails to always go out at a specific time instead for these emails.

To schedule a Flow email to send in a recipients local timezone, you'll want to select the Time Delay>Delay until a specific time of day>enter the time and choose Recipient's Local Timezone:
 

 
Unfortunately, any changes you make are only going to apply to profiles who meet that step moving forward. If your customers are already in the Time Delay waiting for the next email, they will respect whatever the settings were when they reached that step in the Flow.
 
There isn't a way to change this, however, you can change the emails to manual so those profiles move into the "Needs Review" step, and either manually send the emails or opt to schedule to send them a Campaign instead. After all the desired profiles have moved into the "Needs Review" step when set to manual, you can set it back to Live so all other profiles after them will continue to move through the Flow as expected. Changing the Flow back to live will not automatically send to those in the "Needs Review" step; you'll still have to manually send these are the desired time or send them a Campaign instead.

Another thing to note is smart sending. 
Smart Send Time is to not be confused with Smart Sending ​as they are 2 different things.

Smart Send Time uses your business' data to find the optimal time for you to email your customers, maximizing open and click rates as well as helping you to better understand your customers.

Whereas Smart Sending allows you to limit the number of emails or text messages someone can receive from you in a given period of time.

I would definitely read our Help Articles below to get a better understanding of each function.
Smart Send Time in Klaviyo
Guide to Smart Sending in Klaviyo 

Unless the data was coming in from WooCommerce for specific date as a custom property, we couldn’t use that as a filter.

Hope this helped,

Alex