To do so :
Go on the Sequences page (1) using the left panel
Click on the sequence in which you want to setup delays and time slots (2)
3. Once in a sequence, click on one of the blue bricks between your sequence steps, on the left (3)
4. Then, select the number of days (4) and the time slot on which to send the next step (5)
In the above picture, it shows that the 1st blue brick is selected (circled in blue). We picked "2 days after" (4) and the 9am - 10 am time slot. It means that emails 2 of this sequence are always sent at least 2 days after emails 1, from 9 am.
5. Click on Save the sequence (6)
Attention : always set up delays and times slots before adding contacts to your sequence, as it is impossible to update it when your sequence is launched
Important : days that are not included in your sequence planning (see the dedicated article) are considered when counting how many days there between 2 steps. For instance, if you email 1 is sent on Friday, and your email 2 is scheduled 2 days later then it is sent on next Monday.