How should I manage large irregular annual expenses?

[JeffCharles]

We live in Mexico and have family in the US and France, so we've got a
large annual amount planned for travel. However, we do not know in
advance when we will spend it.

My plan is to initially put the full amount in the last month of our
Spending Plan for the year. Then, when we spend travel money, I'll put
that amount in the planned amount for Travel for the current month and
deduct the same amount from the year-end sum in the Spending Plan.
After that, I'll allocate from Income to the current month's Travel
bucket. (I hope that I have explained this clearly.)

This is the best approach I could think of that to give us a realistic
picture of our spending. Is there a better way?

Thanks,

Jeff