The following comments are based on my personal experience whelping quite a few litters of Basenjis over the years.
I never take temperatures with mine as I feel observation is far more accurate as well as less invasive to the bitch. My puppy pen is in my kitchen and I am almost always in the adjacent living room so I can keep an eye on things. When the bitch starts early labor, she will start digging and tearing up newspaper. (I don't put anything other than newspaper in at this point because shredding may result in swallowing and I certainly don't want bits of towels or blanket ingested.) The bitch will feel pressure causing the urge to urinate and/or defecate so I take her out frequently, always under close supervision. As labor progresses, the bitch grows more and more restless and will often whine and look towards me for comfort, or in the case of an inexperienced bitch, in confusion. From the very start of labor to the delivery of the first pup can take anywhere from an hour to 24 hours.
Let us know when they get here!