How to convince ultrasound tech to check gender early

I have an ultrasound tomorrow. Ill be 13 weeks 6 days. But baby has consistently measured 4 days ahead. I would love to just have the tech check and see if there is even a good shot in between the legs. But since my gender scan isn't until 20 weeks, I feel like she'll say no...

Im pregnant with my 5th baby. I already have 4 sons, and I just cannot wait til 20 weeks to know if I'll finally get my girl!

(I feel like its a boy though lol! )

My ultrasound is supposed to take about an hour, but I figured maybe I wouldn't bring it up till she was almost done... ugh idk cuz im so shy!