clearblue advanced digital opk ?

Lauren • 23. Nurse. Married the love of my life 10.5.13.
I normally have a 28 day cycle and began using these tests today for the first time as directed on the package (cd 8) and got a "peak" reading today on my first use? I read it was normal to get a low reading your first day as it gets a baseline level of your hormones. Any experience with this? The helpline told me to wait the 48 hours and try again and call back on Monday if I got another peak reading.