Glow has moved dates ????

Shianne • I`m 20 my partner is 22 we have been ttc for 2 years with 1 MC last year in August at 8 Weeks :( RIP Angel baby xo.
Hey ladies yesterday 12th may 
My AF was due on the 28th, now it says AF due 24th !? I'm really confused right now
Is this normal?? Has this happened to anyone else? Does this mean I'm in my TWW now?? 
When should I test??
Xx baby dust to all you lovely ladies ❤️ xo