Personally, I don't think it's a big deal. Progesterone is very important after IVF/FET... but estrogen is not as crucial. According to my RE, estrogen is usually just given as a precaution...just in case. I guess studies out there have shown little correlation between estrogen supplements and successful IVF outcome. So if I wouldn't worry too much about it...but if you want, you could probably just modify your schedule today, and take two in the early afternoon and then another two at night.
Good luck with everything!
To me, it does not hurt either just less or more one pill but ask your RE.