Advance digital ovulation test

Tyffany • Ttc #1
Hello I'm new to this.
 My hubby and I have been ttc for 5 yrs now.  My problem is I don't ovulate.  This is my 2nd mth on letrizole + <a href="https://glowing.com/glow-fertility-program">IUI</a>.  I finally ovulated w/ letrozole👍.  After several try's w/ clomid= no success👎. 
My question is how do I detect when to call to schedule my <a href="https://glowing.com/glow-fertility-program">IUI</a>?  High or on the peak days of ovulation?  I'm confused.  🙏 2015 will be our year!  
Baby dust and Happy New Years!