First of all
I am a math nerd and because we are totally debt free and living like no one else I may do my bookkeeping a little different than you.
Our main income is once per month and that is what I base our budget on. Any additional that comes in goes into the ffef.
Each month I move a set amount of money to savings, first on paper. I make entries in excel of how much goes to what sinking fund.
Then, still on paper, I subtract any sinking funds that are scheduled to be withdrawn that month. The remaining balance is what should be left in the account for that month.
I then actually only move from checking to savings the amount needed to balance my Excell worksheet. That leaves the money needed to payout to sinking funds in checking.
EXAMPLE: if my monthly deposit is normally 1,000 and I have a 200 sinking fund due that month I only actually only move 800. All bookkeeping is done in excell where I keep track of what is going in and out of each sinking fund, not the actual payments. The actual payment comes put of checking like it was a grocery purchase or something