Here in NY it is actually illegal to feed the lawn before April 1st.  Tha makes sense since the lawn can’t utilize the nutrient until it is actively growing.  Wait until the lawn looks like it is greened up and growing before applying lawn food…late April or early May.  If you are applying crabgrass preventer, wait until the very first lilac flowers are popping open.  Applied too early, it is ineffective.  Here’s a link that you might find helpful: