There's value in both the with and without spend adjust...I like to adjust because it makes the number bigger, hehe!
The beginning, end, or average (money chimp), doesn't make much difference, does it? Oh well, I'll take whatever bit of increase in accuracy I can get if it only takes a one-time change of a formula in my spreadsheet. Actually, my number is kind of rough because it's just my 12 month spend projection linearly applied to the number of days so far in the year. And, as you do, I have lumpy expenditures. It would be a lot more accurate by using actual spending, but that sounds like too much effort for something I'm trying to push out of the spotlight rather than into it.