When to test?

So AF was suppose to visit last Friday and still nothing. I'm currently on day 37 of my cycle. I had barely any spotting last week, boobs have been sore for a week, and mood swings. All which are normal for this time of month. While my husband and I aren't currently trying, we aren't using any BC, we are just avoiding the high % days (plan is to start around May/June). I've never been super regular, but usually I'm not this late. So basically if I am pregnant it would not be a bad thing. My question is how long should I wait before I test? I don't want to buy a test to soon and not get an accurate reading. Is now okay, or should I give it some more time?