In order to track the time/date that campaigns are opened per user can be done by doing the following:
Click on “Reports”
Click on the Campaign that you want to review time/date per user
In the “Summary” section click on the “Opens” summary
That report will provide dates and times of opens for each user.
As for sending follow-up emails per user based on their specific opens’ is currently only possible via email open webhooks via Zapier. However, more to come on this topic, stay tuned!