I had quite a bad 2nd degree tear but I have no idea when it happened. I laboured on gas and air only but didn't feel the tear happen. Afterwards, it took a while to stitch and they gave me some local anisthetic whilst they did that, but I was feeding for the first time so quite distracted. They generally heal pretty quickly afterwards (mine didn't, but this is quite rare - 98% heal perfectly) and I took paracelamol for a couple of days after. I had some particulalr complications and mine didn't heal well, but I have had it redone now and it is fine. Even after the complications, it honestly isn't anything I would worry about next time - more of an inconvenience than anything. Don't worry about it - chances are it won't happen, or if it does it will be minor. Even if its major though, it is still not a big issue.