If sciatica is caused by a single event and not over time, wouldn't it begin straight away or next day?

If sciatica is caused by a single event and not over time, wouldn't you begin feeling the pain straight away?... or at least the next day? This is because someone pushed me forward on a rowing machine at the gym and I felt two crackles to the left of my lower back, but felt no pain with that day, the next, or even the next. The next day I did some stretches to check for pain including a hyperextension and moving my trunk from side to side, although I didn't feel any pain then, I did get some clear shooting pain going down my leg the next day and some prominent pain in the middle bottom of my back. Please help.