When to test??

I'm new here and also new to all of the short forms you are all talking so I'm so confused. When can I take a pregnancy test and it be positive? My hubby and I have been trying only for a couple weeks but I'm eager to grow our family. I have a 16 month old son and we want him to have a sibling so badly and I have extreme baby fever! I am still fertile for a few more days and my period is due in just less than two weeks but I want to take a test! Would it be silly?? What are the odds of it being positive?