preseed?

Y`Marrea โ€ข married to love of my life ๐Ÿ’ mommy of 2 boys๐Ÿ‘จโ€๐Ÿ‘ฉโ€๐Ÿ‘งโ€๐Ÿ‘ฆ #3 10/24/19๐Ÿ‘ฃ๐Ÿ’œ

I want to use preseed but I'm not sure when I ovulate my cycle is super irregular. would it be a waste to use it now or can I use it whenever we have sex?