First pregnancies often don't show until 20 weeks or later, although it varies with the individual. Gender is usually something that they look for at the 18-20 week anatomy scan. They're looking at much more important things than gender (such as whether or not your child's organs are forming properly), but while they're there they can usually tell what gender the baby is if the baby is cooperative. The closer to 18 weeks you are the higher the chance of the tech being wrong. A few women however are unlucky and no matter how many times they do an ultrasound the baby's legs are crossed or the cord is in the way or something like that, so they have no choice but to wait until the birth to find out what they are having.

Some woman with their first they don't start showing until a little later on.

And at your 20 week ultrasound, but you could find out at 16 weeks if you wanted too and the baby isn't shy.

Impossible to say. Different body types tend to show at different times. And it depends on what you consider showing. Some people think it when there pregnant belly is big enough that even a stranger could tell you are pregnant. Some people think is when your belly starts to get round and it is noticeable bigger.

As far as the sex I think an ultrasound could tell now. But most doctors wait until closer to 20 just so there can be no mistakes in determining it. I knew with my second child at 18 weeks.

You can find out the sex in 2-4 weeks and you'll notice that you'll start showing after 20 weeks since it's your first I'm assuming.