We have one we water a neighbor with and one a neighbor waters us. The simplest solution is an agreed upon amount per hour it is on you or them.  If it makes a full circle split the time in half.  If you make a half circle it goes to that half.  Check the hour meter on the panel and if it is anywhere close use it.

It can be difficult at the end of the season making sense the notes that seemed so clear when you wrote them at 3 AM in July, so write a novel instead of shorthand.