Fluctuations in OPK

SJ

Hi.

I am not due to ovulate for another 6 days yet, but as this is my first month TTC I have been taking a test or two each day since my period ended .

I have noticed that today’s test is lighter than yesterday’s (I have taken it twice and it looks the same).

My question is, is it normal for your lines to be darker and then lighter before your peak?

Thanks in advance.