Can I A/B test the delay of the actions within a campaign?
It's currently not possible to do an A/B test on the sending time within Campaign Composer, only message content can be tested.
However, there's a way to set up an A/B test on sending time with messages. Therefore, you need to create two single messages with the same setup, but different sending times - so for example: one in the morning and one in the evening. Next you'll create an A/B test (in the A/B test section) with those two messages. Please find more information on how to set up an A/B test here: https://docs.leanplum.com/docs/ab-testing-a-message