Dollar Tree OPK - 1st timer

Tara • 02.22.16 ZJLA Baby #2 is on his way!!!!
Hey everyone! 
​This is my first time using an OPK. Seems pretty positive to me, right...? Should I test again tomorrow just to see if I just began ovulating? How do I know when it began and when my time frames are?? 
​I came off birth control around the end of May so it kick started my period after 21 days. Since then it flu ayes 24-26 days. Last period was 28 days. So it's hard to know when to test. 
​Any info would be great this is all knew to me! Thank you ?