If you click into the Sequence, you will see high-level' emails sent' data and such on that page. Furthermore, while on the sequence 'Stats' page, If you navigate to the 'Enrollment' tab towards the right of the 'Stats' page beside the 'Steps' tab, you will see each individual contact that was enrolled. From there, the 'Step #' column will let you know which step each contact is currently on.
It might take just a little bit, as there is an algorithm that runs on the backend to make sure all emails don't get sent at the exact same time, and rather splits it up (to not get flagged as spam). Once the sequence starts, it will show that it is on Step 1, Step 2, etc.
You can always click on any individual contact that is enrolled to view their properties, history, etc., and on that popup as well you will be able to see the sent email.