The help text for the sd and ed options
--sd START, --start START::
start date (default: first of this month, format: Y-m-d)
--ed END, --end END::
end date (default: last of this month, format: Y-m-d)
seems to imply a date only argument format (Y-m-d), while it can also have a time part (Y-m-d-HM) as shown in one of the examples:
% ctt track --sd 2013-04-29-0800 test