If your period doesn't come on the day that it supposed to normally.. does this mean your pregnant & to take a test that same day or what?

It does not necessarily mean you are pregnant.
Sure you can take a test. The results may not be accurate. Give yourself about 7 days and then test or call your doctor and let them do a test.

Many women have fluctuations in their periods. There are many reasons for this, including stress, normal changes, sudden weight gain or loss, change in exercise routines, etc...

In taking a pregnancy test, to get optimum results, one should wait a week after the missed period and test using first morning urine.