Should I call off work?

I'll start off by saying I'm a FTM so I have no idea what to expect. I'm 39 weeks and pulled out all the stops yesterday (sex, walking, yoga ball, pineapple, etc) and when I went to sleep at 10:45 was feeling cramping in a pattern. Every 2 minutes I would have an intense squeezing in my lower stomach that lasted 30 seconds each. I counted 6 rounds of this before falling asleep and have a feeling it continued on while I was sleeping.

I can't tell just yet if the same pattern is back this morning, but I'm definitely feeling crampy. I'm worried to call off work and "cry wolf"/have my boss think I'm an idiot if a few days go by and I don't have my baby.

Could true labor be near? Has anyone else had a similar experience and had heir baby soon after?

Thanks in advance!