When to test

So we already have 1 sweet 16 month old. Right now we are wanting to wait before having our second. Well we always use protection except for this past weekend when we got caught up in the moment and didn’t use any. I realized after the fact that it was the last day of my ovulation cycle. Well 2 days after I have started to spot. It makes me really nervous since I always start on the 19th of every month. I’m not sure if I’m just being paranoid or I should be thinking about testing soon. My husband said he would be so excited to have another one now. Please help!!!!!