Will glow auto update period chart?

Samantha • We are expecting baby girl #2 on 10/31! Can't believe the changes coming!I work full time as a Vet Tech and live in Maine.
So my period was supposed to start yesterday, but it didn't. I have some spotting today (hope that's all...) but marked the "X" for yesterday...will Glow automatically update my calendar or do I have to every month if it's a day or two off??