@CRM_Ben
Using an approach as in code below should allow you to get what you're after. This approach will also deal nicely with leap years.
data have;
format DoB date9.;
do DoB='01Jan1995'd to '31Dec2000'd;
output;
end;
run;
/* select all DoB in the next 3 to 9 days based on date of &start_dt */
%let start_dt=28Feb2016;
data want;
format Start_Dt DoB _Start_Dt_aligned date9.;
set have;
retain Start_Dt "&start_dt"d;
_Start_Dt_aligned=intnx('year',Start_Dt,year(DoB)-year(Start_Dt),'s');
if (3 <= (DoB - _Start_Dt_aligned) <= 9) then output;
run;
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