Maybe they will in this case. The forensic use of bugs has to be VERY imprecise. Flies don’t just lay eggs on day one which hatch on day two, etc. etc. Other flies also lay eggs on day two, day three, day four … they are probably still laying eggs on day twenty-one, when the flies from the first eggs are matured. By day 25, the first generation flies are laying their own eggs.
Pick a maggot off the dead body … you can say when the egg was laid. You cannot say it was among the first eggs laid on the body after death.