Advice please

So I got my BFP 6/9/15. I decided to not tell my HB and save it until Father's Day to tell him. On Wednesday night, I had very light spotting and it went away an hour later. And again Thursday morning, then went away. I called the doctor and they wanted me to come in for a HCG test. I decided to hold off until after I tell HB. The lab doesnt process HCG tests on the weekend so I wouldn't have gotten the results until Tuesday anyway. Well yesterday and today, I have been having light cramping, like period cramping. Should I tell my HB now, in case something bad happens before Sunday? Or still wait until Sunday? And if I wait, (or not) how do I even phrase it to him? Before I was just going to put our son in a 'Big Bro' onesie, but now I don't know what to say along with it. 'Hey I'm pregnant, but maybe not for long'? Thanks ladies!