It would help if we knew why you want this delay, and what the trigger is supposed to do after the delay. However, one possibility is to use the DBMS_JOB package in the trigger to create a job that runs at a time a little after the insert. For example:
create trigger trg
after insert on tab
for each row
declare
jl_ob number;
begin
dbms_job.submit
( job => l_job
, what => 'myproc(:new.id);'
, next_date => sysdate+1/24/60 -- One minute later
);
end;
Alternatively, the trigger could insert a row into a special table, and a DBMS_JOB that runs on a schedule e.g. every 10 minutes could process rows in the table that are more than X minutes old.