No, that date has nothing to do with the length of your award, it is a DWP system reminder (probably regarding the winter fuel payment). ESA is an indefinite award that can be reviewed at any time after 3 months following the decision, for this reason claimants are not automatically given a review date. In practice, there will be a 'prognosis' on your claim that will indicate when to expect reassessment. You can find this out by phoning DWP and asking for the 'prognosis' or you can write in and ask for a copy of the ESA85a which will have been filled out by ATOS and should also include a prognosis.
The details in this FAQ will be applicable even though you did not have a face-to-face assessment
ESA medical – what forms to ask for?