LH Surge on OPK? - Need for IUI

Must call doctor for LH surge to do <a href="https://glowing.com/glow-fertility-program">IUI</a>, but need help! 
OPK instructions say test line must be equally dark or darker than control line for LH surge (brand name is Easy@Home). 
1st OPK taken 5/23 (top test strip)
3rd OPK taken 5/25 AM
4th OPK taken 5/25 PM
2.5mcg Letrozole 

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