Calendar changing?

Question

When I charted my positive opk the Calendar changed my period dates? I'm suppose to start on dec 20 but it changed to dec 23! Shouldn't I still start on the 20th?

Answer

Did you get your positive later than cd 14?  I didn't get my first positive Opk until cd16 in the pm and again cd 17 am and pm, once I entered the positive Opk it pushed my af start date from the 8th to the 10th, I think it is because most women don't start their af until 14 days past ovulation, so glow is making adjustments from your predicted ovulation to your Opk confirmed ovulation..

Answer

I would think you should still start on the 20th