The # delimiter is correct for literal dates within the SQL statement (and
in VBA also.)

When adding paramters to a query, do not add the # to the parameter name.

Internally, Access actually stores dates as real numbers, where the integer
part represents the date and the fraction part the time. You can see this
for yourself if you open the Immediate window (Ctrl+G) and enter:
   ? CDbl(Now())

Using text (e.g. may) inside the # is not correct.

For details on how Access interprets date entries, see:
   International Date Formats in Access
at:
   http://allenbrowne.com/ser-36.html