how many rounds of TI before moving to IUI?

Mel
Ok- just finished my 4th round of letrozole with times intercourse- no success. Pretty down about this as I had 3 good follicoles this month. I also had an HSG this cycle- no blockage. We have been TTC for coming up on 1.5 years. 
Our next step is getting my husband tested. I am moving to my 5th round letrozole and I want to try the trigger shot this month. My question has to do with <a href="https://glowing.com/glow-fertility-program">IUI</a>- how did you decide to move to <a href="https://glowing.com/glow-fertility-program">IUI</a> and what was your experience with them.