Why haven't i got an unmarked circle

Question

On today's cd2 i mean my temp was an hour early taken compared to yesterday

Last month chart at beginning & almost all the way through i had full circle and unmarked circles

Answer

Because with only two temps it’s possible that you don’t have a default time for this cycle yet?

Answer

That’s weird-no idea!

Answer

Can you tell me what the circles mean ?? 
This is my chart  and I was wondering why the first two aren’t blue ?

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