Digital OPK’s different results

Hey team, would love your opinions.

I’ve been using the Clearblue Digital opk’s (they’re the only ones that work for me, strips never give me a positive reading).

For the last few days I’ve had low readings (blank smiley faces) until yesterday at lunch time when it jumped straight to a peak reading (static smiley face). I thought “Great! It’s time” but was a little unsure because of the way it skipped flashing smileys altogether, so I used a new stick in new reader an hour later which ofcourse gave me a low reading (they always give a low reading for the first one because it’s setting it’s baseline), but last night I did another and it said low too, and thismorning said low aswell. Could the peak reading on the original reader been false? Or could I have had my surge that quickly?