Not usually. Sometimes a fermentation can happen very quickly (a matter of hours) and you’ll have missed it during the night. (This can happen with some dry yeast and especially if you didn’t cool the wort enough before pitching.) Look for tell-tale signs that you had some activity – usually there will be a ring of scum an inch or so above the level of the liquid. You can also take a hydrometer reading. Also see the above two answers.