BBM:
I think that's also likely.
Timing the drive, mapping out his route options, etc.
Also to nail down her departure times to drop the kids off at school as well as her arrival time back at the home.
As I'm talking about school, it occurs to me that one of the driving factors behind the timing of this murder may have been school calendar year. I'm not sure when the school year ends there, but I'm assuming it's not year-round.
With the kids getting out of school for summer vacation soon, the schedule would have become much less predictable. The kids would have been home during the day, too.
His opportunities to catch her alone and unawares would have become much more limited.
JMO.