I'm not sure what you have been instructed by your doctors/which kind of device you are getting. Usually they measure every 20 mins or so.
I recommend taking note of the time and what you are doing and were doing prior with each measurement.
It's very important to note whether you were upright (standing, sitting or walking) or supine, for orthostatic intolerance.
May want to also note at what times you eat - there may also be a correlation between BP and digestion.
This is really a tool for you to learn about your body.