Going for iui when opk is positive 😋 help please‼️‼️

Hi everyone! Im going for my <a href="https://glowing.com/glow-fertility-program">iui</a> the very next day of positive? Usally cd 15 the line is as dark and then cd 16 is darker..... when should i consider positive 😬😬 cd 15 to go inn for <a href="https://glowing.com/glow-fertility-program">iui</a> cd 16 or cd 16 to go inn for <a href="https://glowing.com/glow-fertility-program">iui</a> cd 17?:/