A little confused🤔

Hey everyone🙈 so I’ll get to the point of my post but I have to period apps and glow I recently just got and it’s saying today I should of started my period but my pc calendar said my period isn’t until 3 more days so idk 🤷🏼‍♀️ which one I should go by I put the correct info, but should I test or just wait any advice to this crazy question is so helpful also I have a five year old little girl so I’m not a first timer just was always told everything doesn’t always go the same.