Some tests can be taken a few days before your period is expected to start. Be sure to read the instructions for the test. The results may be more accurate if taken after you miss your period.
As far as brand I would NOT reccommend the EPT test (the one that shows a + or -) I bought a kit with two tests. The first time I took it, it showed a line - I thought it was negative. I took the second test a week later because I still had not started and I was having a lot of
pregnancy symptoms. The result was the same, but this time I noticed that the line was vertical and the examples on the box were either a plus + or a - (horizontal line). I asked my husband wht that meant and he siad he thought it meant that we needed to buy a different brand of test! The next test we bought showed one line for negative and two for positive (I think it was First Response?). There were definitely two pink lines!