Period/ GLOW help!!

Diana • Sun, Dec 14

Does everyone go by what Glow says?? I am like clock work every 28 days (except last month when I was a week late)...but glow keeps telling my period is coming the 24th. I would think maybe the 26-28? I am just curious because I wouldn't want to test to early and be disappointed. Do you usually judge by what glow says or by your own calendar??