Fertility low straight to peak?

Mariah
Hello!
This is the first cycle I've tried using the CBOPK, I tested yesterday morning and it was low (circle no smiley face), then I tested tonight and I got peak fertility (non blinking smiley face) now I'm worried I missed my fertile window? Has this ever happened to anyone? The ovulation calculators I've been using say I shouldn't start my fertile window until Thursday. HELP!?