I'm 39 weeks/3 days. Had my Dr appt this morning and my blood pressure was a little higher than…

I'm 39 weeks/3 days. Had my Dr appt this morning and my blood pressure was a little higher than normal. They want to see my back on Friday to take it again. In the meantime I'm supposed to be measuring his movement. I haven't done this before as he moves so much I didn't find it necessary plus it seemed confusing on how to do it. Anyone know the easiest way?