That's how it happened for me the first time, one survived, surprise surprise, we called him nemo! It was my second ever fish purchase way back in 2005, I got a pair of Cory, one each, they bred lots! I didn't even know what the eggs were! Then we saw the shimmy T position and worked it out from there using the internet. Then I made a point to document it because it's such a great thing. I am not the first though.
It's easy to sex the fish, females noticeably broader through the pectoral fin region, also longer by 2.5cm/1" or slightly more and generally much more full throughout the body. if they breed once they will breed every six weeks or more if you want. Really that's a lot of eggs though!
Like I say it really is satisfying but think about the fry, some will need to be destroyed, I think it's better to remove runts, your views may differ.
Also you need somewhere to grow them on. 6-8 weeks before they are really big enough, maybe longer depending on what you plan to keep them with.
It is worth it.