How can I use a unixtimestamp as a timerange filter like with earliest & latest in the first pipe?

Hi, my events have a field with epochtime which I want to use in the very first pipe to filter the search Of course I can do it like sourcetype=foo field<=1461110400 Is it somehow possible to use this filter as a readable date in the first pipe? Like in earliest earliest="04/20/2016:00:00:00" Cheers Heinz