When to test if pregnant or not?

❤Hey there, I am wondering whether to test for pregnancy or not as my last period was on 16/12/16 was supposed to start my period middle of January and I'm still waiting for AF to arrive. My cycles range from 34-40 but too scared to go get a test just in case it's a negative!! I've been having cramps well tingling on my left abdomen, increased hunger, tired and dizzy once or twice but not fainted!! Help would be appreciated!! ❤Xxx