Sex before LH surge

I am wondering if anyone has successfully conceived by having sex the day BEFORE LH surge? I was using another tracking app that told me the 13th was one of my fertile days, and then glow telling me my fertile window was like a day or two later. However I did have sex the day before a very positive ovulation test which I’m assuming was my surge since it was negative the day before. Any feedback is appreciated as this is my first month trying!