Bill, be careful when fiddling with toe nails, Patricia is right about the 'v' but I would recommend seeing a podiatrist (or whatever they call themselves these days) unless you want to end up with only nine nails (like me, yuck).
Another tip is to get a very tiny piece of cotton wool, roll into a small ball and push it down under the offending corner of the nail with an orange stick, to raise the nail up and away from the skin. It doesn't hurt, you can't see it and it can stay there for quite a while. It encourages the nail to grow straighter.
My doctor told me this many years ago and it really works.
About match head size when it is compressed Boo, but it would depend on the individual. Push it down well under the nail so you can't see it. I have left it in for up to a couple of weeks at a time and had baths, showers, etc. and it hasn't moved. Has also worked on my son's ingrown toenails on many an occasion.
It really really works and I wish I had been told years ago instead of having horrible treatment on my toes as a child/teenager.